Is a father considered sinful for abandoning his children and refusing to communicate with them after a dispute with their mother and his separation from her, even if he provides for all their material needs?

It is not permissible for a Muslim to abandon his brother for more than three nights, and the better of them is the one who initiates the greeting of peace. So, whoever abandons for more than three nights and then dies, he enters the Fire. And whoever abandons his brother for a year, it is as if he has shed his blood. The questioner must take the initiative to mend what he has corrupted. It is not permissible to abandon someone for more than three nights except for a legitimate reason. It is not permissible to abandon children for more than three nights without a legitimate justification. Children must maintain ties with and honor their father, for disagreement between parents does not permit children to cut ties with either of them. The father is responsible for raising his children, and their need for upbringing may exceed their need for money.