Mukhtasar Bukhari

Narrated Abdullah bin Amr (may Allah be pleased with them) that the Prophet Muhammad (peace be upon him) said: "The greatest of the major sins is that a man abuses his parents." The people asked, "How can a man abuse his own parents?" The Prophet (peace be upon him) said: "A man abuses another man's father, and that man (in return) abuses his father... and he abuses another man's mother, and that man (in return) abuses his mother."