Man's new wife is not responsible for raising his children from an ex-wife
25-8-2014 | IslamWeb
Question:
after the death of his wife who will raise or upbring the children ?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Raising the children and taking care of them is a joint responsibility between both parents. Allaah, The Exalted, says (what means): {O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones, over which are [appointed] angels, harsh and severe; they do not disobey Allaah in what He commands them but do what they are commanded.}[Quran 66:6]
Moreover, ‘Abdullaah ibn ‘Umar 
reported that the Prophet, sallallaahu ‘alayhi wa sallam, said: “Each of you is a shepherd and he is responsible for his herd. A leader is a shepherd and he is responsible for his herd; a man is a shepherd and he is responsible for his family; a woman is a shepherd and she is responsible for her husband’s house and those under her care...” [Al-Bukhari and Muslim]
If the mother has passed away, the father becomes primarily responsible for taking care of the children and bringing them up, whether they live in his house or any other house, like his mother’s, for example. He is obliged to take care of them and teach them well.
It should be noted that if the widowed husband got married, his new wife is not obliged to accept sharing her accommodation with his children in the same house except in certain cases identified by the jurists. She is not responsible for taking care of and raising her husband’s children at all. However, if she offered her husband assistance in taking care of his children and offering them good upbringing out of desire for the reward of Allaah, this is an indication of her noble character and she will be generously rewarded for that.
For further information, please refer to Fataawa 84237 and 88783.
Allaah Knows best.