Imam Ahmad was asked: which of the parents has greater right? He said: the mother. He used to say: birr (kindness) to the parents is an expiation for major sins. He held that obeying them in what is permissible is obligatory; obeying them in disobedience to Allah is not, but kindness to them remains. He said: do not raise your voice above theirs, do not walk in front of them, do not call them by their names, and do not sit until they sit. If a man's parents call him while he is in voluntary prayer, let him cut it short and answer them — except in the obligatory prayer.