What should we do with a father who abandoned us, mistreated our mother, and did not ask about us for many years, and now he is trying to return? Should we communicate with him, or leave him to God, or supplicate for his guidance?

If a father commits wrongdoing and fails in his duties towards his children, they are not permitted to abandon him or prevent him from entering his home. This constitutes an unlawful act of disobedience (ʿuqūq), which is among the gravest sins. The father's right is immense, and showing him dutifulness and good companionship is obligatory, regardless of his condition, even if he were a polytheist commanding shirk (associating partners with God).

Indeed, Allah Almighty commanded good companionship with parents, even if they strive to make their child commit shirk. In such a case, the child should not obey them in shirk, but should still accompany them in this world with kindness. The children must repent to Allah and apologize to their father, striving to be dutiful and good to him, while also enjoining him to what is right and forbidding him from what is wrong gently and respectfully, and working towards reconciliation between him and their mother.