As-Salaam alaikum,
Sometimes Allah Ta'ala gives astonishing and extraordinary miracles to His protected friends, (the Awliyaa), which tend to increase the believers in faith and throw disbelievers down in humiliation. Such assistance also break the bad habits of the soul and break the normative laws of creation. The evidence for the existence of miracles have been firmly established in the Book (Holy Qur'an) and the Sunnah.
Examples:--
(1) In Surat Namli of the Holy Qur'an, concerning one of the companions of truth...the Siddequun..and a follower of Prophet Suleiman, peace be upon him, that is Asif Ibn Barkhiya, Allah, Subhanahu Wa Ta'ala says:--

"HE WHO POSSESSED KNOWLEDGE OF THE BOOK SAID, 'I WILL BRING IT
(the Throne of Bilqis) TO YOU BEFORE YOUR GLANCE RETURNS TO YOU." (27:40)

Here, we see a man who was neither a Prophet or Messenger brought the throne of the Queen Bilqis from Abyssinia to Jerusalem faster than the blinking of an eye. This was by the Divine Permission of Allah Ta'ala, so what can the rejectors say about the miracle of the Awliya after reading this Qur'anic ayat?

(2) Concerning the people of the cave (ashab-kahfi) in chapter 18 of the Holy Qur'an, Allahu Subhanahu Wa Ta'ala says:--

"..BEHOLD, THE YOUTH BETOOK THEMSELVES TO THE CAVE: THEY SAID, OUR LORD!
BESTOW ON US MERCY FROM THYSELF, AND DISPOSE OF OUR AFFAIR FOR US IN THE
RIGHT WAY.
THEN WE DRAW (a veil) OVER THEIR EARS, FOR A NUMBER OF YEARS, IN THE CAVE
THEN WE AROUSED THEM..." (18:10-12)

Realize that the ashab-kahfi slept 309 lunar years in the cave without food or drink-- and this was a miracle. Their turning left and right in order not to injure their sides was also a miracle, so was their being awaken after sleeping 309 years!!

And from the Sunnah, let us consider just 2 examples from several, where "Umar Ibn Khattab, may Allah be pleased with him, was one Friday giving the Khutba upon the minbar of the Prophet, Sallallahu alaihi Wasallam, when suddenly he saw the enemies and the Muslims at the very extreme of the country of the Persians. The enemy armies desired to move up the mountain in order to defeat the Muslims and inflict harm upon them.
The Amir of the Mujahiduun at that time was Sariya Ibn Hassan, may Allah be pleased with him. Umar, while he was giving the sermon, suddenly shouted- 'To the Mountain O Sariyaa'!!
Sariyaa heard the voice of the Amir'l Mumineen Umar and he with the army of the Muslims moved up the mountain. By means of this maneuver the Muslims attaine victory and defeated the disbelievers."

Here, Allah manifested 2 miracles upon the hands of Umar Ibn Khattab: (1) The ability to see more than a month's travel and (2) The ability of Sariyya to hear the voice of Umar from that same distance.
This is an extraordinary event/achievement, but moreamazing than that is the modern Muslim today who will doubt that, while at the same time he believes in the voice he/she hears on the radio from America and London and in the images he sees from cable television network form many parts of the world. Thus, he believes in the abilities of created beings and rejects the Omnipotence of the Creator. Subhanallah!!

In the Nafs'r-Rahman, it was related that "a man was walking in the road when a woman passed him whom he thought was exceedingly beautiful. He then turned and stole a glance of her beauty. When he finally entered upon Utham Ibn Affan, may Allah be pleased with him, he said:- 'What is wrong with a people that when they enter my home and I see upon their eyes the traces of adultery?" This miracle of Uthman was a validation of the tradition narrated by al-Hakim and al-Bazzari on the authority of Anas, may Allah be pleased with him, when the Prophet Sallallahu alaihi Wasallam said :--" There are slaves of Allah who recognize people by their facial features."
Imam al-Azizi said, "They are shown what is in their natures and states by means of their physiognomy." This was the reality of the miraculous station of Uthman, may Allah be pleased with him. For he was drowned in the sea of witnessing Allah until He favored him by removing the cover from his sight where he saw the internal nature of people!.