Sahih Bukhari

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