The Book of Faith (Kitab Al-Iman)

Muslim :: Book 1 : Hadith 162

It is narrated on the authority of 'Abdullah b. Amr b. al-'As that the Messenger of Allah (may peace be upon him) observed: Abusing one's parents is one of the major sins. They (the hearers) said: Messenger of Allah, does a man abuse his parents too? He (the Holy Prophet) replied: Yes, one abuses the father of another man, who in turn abuses his father. One abuses his mother and he in turn abuses his (the former's) mother.

Source materials are from the University of Southern California MSA site
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