What is the ruling on someone whose mother died while angry with him?

Disobedience to parents, especially the mother, is a serious matter and a major sin. Whoever's mother dies angry without just cause has indeed disobeyed her. He must offer sincere repentance, for Allah accepts repentance and thereby erases sins, as stated in the two noble verses: "And He it is Who accepts repentance from His servants and pardons sins, and He knows what you do," and "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'"