Narrated `Abdullah bin `Amr:
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."