Sahih al-Bukhari Book 78, Hadith 3
A man said to the Prophet, "Shall I participate in Jihad?" The Prophet (ﷺ) said, "Are your parents living?"
The man said, "Yes." the Prophet (ﷺ) said, "Do Jihad for their benefit."
A man came to Allah's Messenger (ﷺ) and said, "O Allah's Messenger (ﷺ)! Who is more entitled to be treated with the best companionship by me?" The Prophet (ﷺ) said, "Your mother." The man said. "Who is next?" The Prophet said, "Your mother." The man further said, "Who is next?" The Prophet (ﷺ) said, "Your mother." The man asked for the fourth time, "Who is next?" The Prophet (ﷺ) said, "Your father. "
Allah's Messenger (ﷺ) said. "It is one of the greatest sins that a man should curse his parents." It was asked (by the people), "O Allah's Messenger (ﷺ)! How does a man curse his parents?" The Prophet (ﷺ) said, "'The man abuses the father of another man and the latter abuses the father of the former and abuses his mother."