Bismillah.

It is very unfortunate and painful that some fathers fail to perform their duties towards their children as Allaah has commanded them to do; they do not protect themselves, their wives and their children from the Hellfire. In some cases, they not only fail to raise their children upon honesty, but worse than this, they deliberately raise them as liars by teaching them to deceive and swindle others, claiming that they are thereby teaching them how to be intelligent and diplomatic in their dealings with others.
Some teach their children how to be aggressive and attack and oppress others, claiming that they are thereby raising them to be brave.
Another group teach their children the ways and manners of the disbelievers and how to imitate them, claiming that they are thereby raising them in a modern and civilised way.
Having excessive trust in children:
Fathers must know who their children befriend, what they bring back home with them and especially where their daughters go and with whom.
Some fathers are unaware that their children possess indecent pictures, immoral movies and even drugs. Others are unaware that their daughters go to the markets and malls especially to meet Satan (i.e., her boyfriend); others do not know that their daughters smoke with their female friends when in their houses.
Those who are not watchful over their children will not escape on the Great Day of Resurrection from the torment from which nobody can escape. Anas narrated that the Prophet said: "Allaah will ask everyone about those whom he was entrusted with." [An-Nasaa'i & Ibn Hibbaan]
Spoiling children:
Some parents are too emotional and tend to spoil their children, to the extent that perhaps their children have never heard the word "no" to anything they requested of their parents. The result of this is a generation who cannot cope with the expected problems of life and who, therefore, break down at the first problem they face. We do not say that parents should be harsh on their children and refuse all their requests, but rather, parents should not surrender to their emotions. 'Umar said: "Get yourselves accustomed to harshness because bounties are not always available."
Imaam Ibn Al-Qayyim said: "The parent must keep his child away from laziness, extra comfort and being spoilt, and should raise him upon the opposite of these. He should get him used to exerting effort because laziness has evil consequences, which will cause eventual deep regret; on the other hand, exerting effort and getting used to striving in life is praiseworthy and has good consequences whether in this life or the Hereafter, or both; this is because attaining high ranks in this life and the happiness in the Hereafter are only achieved through hard efforts and striving."
Imaam Al-Ghazaali said: "A father must protect his child by raising him upon good morals and keeping him away from evil company; he must not make him accustomed to having an easy life and must not make entertainment and joy be his main interest, because this will result in the child wasting his life in endeavouring to attaining these pleasures and joys."
Treating children unequally:
A contemporary and evil social phenomenon that exists within some families is that they fail to treat their children equally and fairly. Some parents favour one or more of their children over others by giving them extra gifts, which is prohibited unless there is an Islaamic justification for doing so, such as if the child is sick or has a debt to pay off, or has just completed memorising the Quran, or parts of it; other justifiable excuses for favouring a child over the others is when he cannot find a job whilst having a large family to support, or if he happens to be a student of knowledge who cannot work and seek knowledge at the same time. A father who does favour one of his children over the others, due to such valid circumstances, must have the intention that he would have helped any of his children in such a manner, if the circumstances were the same. The general evidence that parents must be just is the saying of Allaah (which means): "...Be just; that is nearer to righteousness and fear Allaah..." [Quran 5: 8]
The specific evidence for it is what was reported on the authority of An-Nu'maan Ibn Al-Basheer who said: "My father took me to the Messenger of Allaah and said to him: 'I have gifted one of my slaves to this son of mine.' The Messenger of Allaah asked: "Have you given such a gift to every son of yours?" He replied, 'No.' Thereupon, he said: "Take this gift back." So my father came back and revoked his gift". [Al-Bukhaari & Muslim] In another narration of this incident, he said: "Be fearful of Allaah and treat your children justly." Yet in another narration that is found in the book of Imaam Muslim the Messenger of Allaah said: "I am not going to bear witness to this act of injustice."
Imaam Ahmad said: "A son may be given twice the share of the daughter, as is the case when distributing the will."
One who looks at the situation of some families will find that some fathers do not fear Allaah when giving gifts to their children. They give them to some of their children and deprive others; or, they may give to the children of one of their wives whilst depriving the children of others, which implants enmity and hatred amongst the children and cause them to not be kind and dutiful to their father; this may in turn lead to the collapse of the family. The Prophet asked a man who did not treat his children fairly: "Do you not wish that they will all treat you with goodness and dutifulness?" [Muslim & Ahmad]
Some people mistakenly believe that correctly raising children is limited to feeding them properly and providing them with adequate clothing and education, and they disregard instilling high morals and religious principles and etiquettes in them.
Others fall into the mistake of thinking that once they have placed their children in school, the school shoulders the sole responsibility of their cultivation.
Some fathers panic as soon as their child's temperature rises slightly and rush in all directions looking for a doctor or a hospital; while on the other hand, they are indifferent to the prohibitions or major sins that the same child commits. We ask: what is the temperature of the Hellfire? Why does the father panic at such a small temperature increase but fail to protect his child from the Hellfire?
There are some parents who become extremely angry and lose their sleep when their child falls behind his classmates and performs worse than them; they may hire a private tutor in order to make him catch up, but, when he neglects his prayers or even totally abandons them, or if he commits prohibitions or major great sins, they will not even rebuke him for it.
Similarly, there are fathers who become enraged when their child disobeys one of his orders, but are careless when the same child disobeys Allaah and shuns His commandments.
The father who neglects his children and does not guide them to adhere to the Quran and the Sunnah of the Prophet and fails to raise them upon Islaamic tenets, beliefs and morals, will undoubtedly have his children divert and become misguided, and they may even become dangerous individuals in the community.
Do not forget that a righteous son is a source of goodness for you after your death as the Prophet said: "When a servant (of Allaah) dies, his (good) deeds will cease, except for three (kinds of deeds): A charity with continuous effect, a kind of knowledge from which people draw benefit, and a good son who prays to Allaah for him." [Muslim]
Abu Hurayrah narrated that the Prophet said: "The rank of a man would be raised in Paradise, and he would ask why, and he would be told: `It is due to your son supplicating for your forgiveness.`" [Ibn Maajah]
Finally, the Prophet said: "He who recites the Quran, studies it and acts according to its teachings will be dressed on the Day of Resurrection with a crown of light, the light of which is like that of the moon, and his parents will be dressed in two garments the like of which do not exist in this life; they will ask: `How did we attain it?`, they will be told: `It is due to your child memorising the Quran.`" [Al-Haakim]