"Allah سبحانه و تعالى selected a group to accompany the Prophet صلى الله عليه وسلم and receive the Shariah from him; they are the best of his ummah."
[This article is part of a free translation of 'aqidah ahl al-sunnah wa al-jama'ah fi al-sahabah al-kiram by 'Abd al-Muhsin al-'Abbad]
A manifestation of Allahs mercy and favour upon His slaves is that He sent to them a Messenger صلى الله عليه وسلم to convey His message, guide them to all that is good and warn them from all that is harmful. The Prophet صلى الله عليه وسلم assumed this capacity and accomplished the trust borne on him in a perfect manner; he guided his nation [ummah] towards every good, warned them from every evil and advised them in a sincere and manifest way.
Allah سبحانه و تعالى selected a group of people to accompany the Prophet صلى الله عليه وسلم and receive the Shariah from him, they are held to be the best of his ummah, which in turn is the best of all ummahs. Allah honoured them with companionship of His Prophet صلى الله عليه وسلم and favoured them in this life by enabling them to see him and hear his speech directly from his noble mouth; that indeed is the favour of Allah, He gives it to whoever He wills and Allah is the Possessor of great bounty.
The Companions رضي الله عنهم conveyed the light and guidance Allah had sent the Prophet صلى الله عليه وسلم with in an impeccable manner. They attained an immense reward for their companionship of the Messenger of Allah صلى الله عليه وسلم, for the jihad they engaged in alongside him and the great efforts they expended in spreading Islam. Even though they are a people who have passed away long ago, they remain in constant receipt of rewards for the Prophet صلى الله عليه وسلم has said, Whosoever calls to guidance has a reward equal to the reward of one who acts upon the guidance without the latters own reward decreasing in any way as established from the Messenger صلى الله عليه وسلم in a hadith related by Muslim in his Sahih .
Allah سبحانه و تعالى has praised them in His Honoured Book as has the Messenger صلى الله عليه وسلم and this suffices as a testament to their excellence and nobility. Allah says,
And the former, the first from amongst the migrants [muhajirun] and the helpers [ansar], and those who followed them in righteousness, Allah is pleased with them and they are pleased with Him. And He has prepared for them gardens of which rivers flow below, abiding therein forever, that is the great success.
Allah سبحانه و تعالى says, Muhammad is the Messenger of Allah, and those with him are harsh against the disbelievers and merciful amongst themselves. You see them bowing and prostrating (in prayer), seeking bounty and pleasure from Allah. Their mark (of faith) is on their faces from the effect of prostration; that is their similitude in the Torah, and their similitude in the Gospel [Injil] is like that of a seed which sends forth its shoot, then makes it strong, then thick and then causing it to stand erect on its stem thereby delighting the sowers - that He may make the disbelievers enraged with them. Allah has promised those among them who believe and work righteous deeds, forgiveness and a great reward.
The clause, that He may make the disbelievers enraged with them carries a grave judgement and harsh warning for one who is infuriated by the Companions or has in his heart any hatred for them.
Allah سبحانه و تعالى also says, ...Not equal amongst you are those who spent and fought before al‑Fath  (with those who did so later). Such are greater in rank than those who spent and fought afterwards; Allah has promised all of them the best (reward), and Allah is well aware of what you do.
Allah سبحانه و تعالى says, when specifying those eligible to receive booty, (There is also a share in this booty) for the poor Muhajirun, who were expelled from their homes and wealth as a result of seeking the bounty and pleasure of Allah; they give aid to Allah and His Messenger. They are indeed the truthful ones. And those who lived in Ad-Dar (Madinah) and believed before them, love those who have emigrated to them and have no jealousy concealed in themselves to that which they (i.e., the Muhajirun) have been given. They give preferences to others over themselves even if they themselves are in need; and those protected from their own covetousness, they indeed are the successful ones. And those who come after them say, Our Lord, forgive us and our brothers who have preceded us in faith [iman]; and do not place in our hearts any hatred for those who have believed. Our Lord, You are indeed, full of Kindness, Most-Merciful.
This last passage consists of three verses from Surah Al-Hashr: the first addresses the Muhajirun رضي الله عنهم, the second the Ansar رضي الله عنهم and the third are those who come after the Muhajirun and Ansar who seek forgiveness for them and ask Allah سبحانه و تعالى not to place any hatred for them in their hearts. Anyone not belonging to one of these three groups is wretched and entrapped by the snares of Shaytan; and this is why A`ishah رضي الله عنها said to Urwah Ibn Az-Zubayr رضي الله عنه in reference to some of these forsaken people, They were ordered to seek forgiveness for the Companions of the Messenger of Allah and instead reviled them!
Muslim رحمة اللہ علیه related this towards the end of his Sahih ; and An-Nawawi رحمة اللہ علیه on commenting on this hadith and referring to these verses states, and with these verses, Imam Malik رحمة اللہ علیه supported his judgment: that one who reviles the companions رضي الله عنهم has no right to a share in the booty as Allah allowed it only to those who come after them who specifically seek forgiveness for them. 
Ibn Kathir رحمة اللہ علیه stated in his Tafsir , How excellent indeed is the finding derived by Imam Malik رحمة اللہ علیه from this verse: that the Rafidhi  who curses the companions رضي الله عنهم has no share in the booty as he lacks the quality found in those whom Allah praises on account of their supplication
Numerous hadiths also bear testimony to their status, the Prophet صلى الله عليه وسلم has said: The best of people are those living in my generation [qarn], then those who follow them, then those who follow them Al‑Bukhari, Muslim and others related this hadith by way of the Companions Imran Ibn Husayn رضي الله عنه and Abdullah Ibn Masud رضي الله عنه.
Muslim رحمة اللہ علیه also related it via Abu Hurayrah رضي الله عنه with the following wording: The best of my ummah is the generation in which I have been sent, then those who follow them, then those who follow them and Allah knows best as to whether he (i.e., the Prophet صلى الله عليه وسلم) repeated that statement a third time. 
Muslim رحمة اللہ علیه relates it by way of A`ishah رضي الله عنها saying, A man asked the Prophet, Who are the best people? He replied, The generation which I am in, then the second, then the third. 
In both Sahih Al-Bukhari رحمة اللہ علیه and Sahih Muslim رحمة اللہ علیه, Abu Saeed Al‑Khudri رضي الله عنه relates that the Messenger of Allah صلى الله عليه وسلم said, A time will come upon people, when a group of them will embark upon a military expedition, whereupon it will be said, Is there amongst you anyone who has accompanied Allah's Messenger صلى الله عليه وسلم? They will say, Yes. And so victory will be bestowed upon them. Then a time will come upon people when a group of them will embark upon a military expedition, whereupon it will be said, Is there amongst you anyone who has accompanied the companions of Allah's Messenger صلى الله عليه وسلم? They will say, Yes. And so victory will be bestowed upon them. Then a time will come upon people when a group of them will embark upon a military expedition, whereupon it will be said, Is there amongst you anyone who has been in the company of the companions of the companions of Allah's Messenger صلى الله عليه وسلم? They will say, Yes. And so victory will be bestowed upon them. 
Ibn Battah رحمة اللہ علیه relates that Ibn Abbas رضي الله عنهما said, Do not revile the Companions of Muhammad! As an incident in which any one of them participated in, even for a single hour (with the Messenger of Allah), is better than forty years worth of deeds by any one of you.
And in the narration of Waki رحمة اللہ علیه, ...is better than an entire life spans worth of deeds by any one of you.
When Saeed Ibn Zayd رضي الله عنه listed the ten Companions رضي الله عنهم given glad tidings of being from amongst the people of Paradise, he remarked: By Allah, an incident in which any one of them participated in with the Messenger of Allah صلى الله عليه وسلم, whereby his face became dusty and dishevelled, is better than the deeds of any one of you, even if he were to live the duration of Nuh. Abu Dawud رحمة اللہ علیه and At-Tirmidhi رحمة اللہ علیه related it .
Jabir رضي الله عنه reported that it was said to A`ishah رضي الله عنها, There exists certain people who speak ill about the Companions of the Prophet, including Abu Bakr رضي الله عنه and Umar رضي الله عنه! to which she replied, And why are you so amazed at such a thing? Their deeds ceased , so Allah desired that their reward should not. Ibn Al-Athir رحمة اللہ علیه recorded this narration in his book Jami Al-Usul.
A proof for this fact (mentioned by A`ishah رضي الله عنها) is the saying of the Prophet صلى الله عليه وسلم in the authentic Hadith, The bankrupt person from my ummah will be the one who will turn up on the Day of Resurrection having prayed, fasted and given zakah, but he comes having hurled abuse upon this one, slandered that one, unlawfully consumed the wealth of someone else, shed the blood of another and struck yet another; so his good deeds will be credited to this one, that one and so on. If however, his good deeds are depleted before his account is settled, then a compensatory amount of their sins will be cast upon him, and he will then be thrown into the Fire. 
Al-Bukhari رحمة اللہ علیه relates in his Sahih from Abu Saeed Al-Khudri رضي الله عنه that the Prophet صلى الله عليه وسلم said, Do not revile my companions! For if one of you were to spend in charity the weight of Uhud in gold, it would not be equal to a mudd  spent by anyone of them, nor half of it. 
Muslim رحمة اللہ علیه relates the same hadith from Abu Hurayrah رضي الله عنه that the Prophet صلى الله عليه وسلم said, Do not revile my companions! Do not revile my companions! For by the One Who my soul is in His Hand, if one of you were to spend in charity the weight of Uhud in gold, it would not be equal to a mudd spent by anyone of them, nor half of it. 
Muslim رحمة اللہ علیه also relates it from Abu Saeed Al-Khudri رضي الله عنه with the following wording, An argument transpired between Khalid Ibn Al‑Walid رضي الله عنه and Abdurrahman Ibn Awf رضي الله عنه, whereupon Khalid رضي الله عنه reviled Abdurrahman رضي الله عنه, at that the Messenger of Allah proclaimed, Do not revile any one of my Companions! For if one of you were to spend in charity the weight of Uhud in gold, it would not be equal to a mudd spent by anyone of them, nor half of it.' 
If the many deeds of Khalid Ibn Al-Walid رضي الله عنه, and others like him from amongst those who accepted Islam after Al‑Hudaybiyyah, are of no comparison with a few deeds of Abdurrahman Ibn Awf رضي الله عنه and others like him who accepted Islam early on, bearing in mind that all were honoured with having accompanied the Prophet صلى الله عليه وسلم, how will the comparison fare between those who did not accompany the Prophet صلى الله عليه وسلم at all and these exemplary people? The difference is without doubt enormous; and that indeed is the favour of Allah, He gives it to whoever He wills and Allah سبحانه و تعالى is the Possessor of great bounty.
These are some of the Quranic verses and prophetic narrations confirming the excellence of these virtuous people - the like of whom has never been and nor will there ever be.
See also: The Sahaba (Companions - رضي الله عنهم) - http://www.muftisays.com/forums/nabi-%28s%29-sahaabah-stories/5863/the-sahaba-%28companions%29-%28radiallaahu-anhum%29.html
1. Sahih Muslim/ Kitab Al-Ilm.
2. The peace treaty which occurred between the Muslims and Quraysh at Al-Hudaybiyyah in the sixth year after the Hijrah.
3. Sahih Muslim, Book of Tafsir.
4. Sharh Sahih Muslim, Vol. 6, Chapter 18, Pg. 158, published by Dar Ar-Rayan, Cairo, 1st edition 1987.
5. Tafsir Ibn Kathir, Vol. 4, Pg. 339, published by Maktabah Al-Ulum wa Al-Hikam, Madina, 1994.
6. Rafidhi: one who is attributed to the Rafidhah: a term representing one of the three main groupings of the Shiah.
7. Sahih Al-Bukhari, Al-Shahadat,Al-Manaqib & Ar-Riqaq, Sahih Muslim/Fada`il As-Sahabah, At-Tirdmidhi/Al-Fitan & Ash-Shahadat, An-Nasa`i/Al-Ayman wa An-Nudhur and Musnad Imam Ahmad.
8. Sahih Al-Bukhari/As-Shahadat,Al-Managib & Ar-Riqaq, Sahih Muslim/Fada`il As-Sahabah, At-Tirdmidhi/Al-Manaqib and Musnad Imam Ahmad.
9. Sahih Muslim/ Fada`il As-Sahabah.
10. Sahih Muslim/ Fada`il As-Sahabah.
11. Sahih Al-Bukhari/ Al-Manaqib & Sahih Muslim/ Fada`il as-Sahabah.
12. Abu Dawud/ As-Sunnah & At-Tirmidhi/ Al-Manaqib.
13. i.e. by their death.
14. Sahih Muslim/ Al-Birr wa As-Silah wa Al-Adab.
15. A mudd is equivalent to a dry measure of an average mans two palms.
16. Sahih Al-Bukhari/ al-Manaqib.
17. Sahih Muslim/ Fada`il as-Sahabah.
18. Sahih Muslim/ Fada`il as-Sahabah.