Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "A man's reviling his own parents is a major sin." The Companions (may Allah be pleased with them) said: O Messenger of Allah! Does anyone revile his own parents? He (peace and blessings be upon him) said: "Yes; he reviles someone's father, so that person reviles his father; and he reviles someone's mother, so that person reviles his mother."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 21086