Sahih Al Bukhari – Book of Good Manners And Form (Al-Adab)

Volumn 008, Book 073, Hadith Number 007.
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Narated By Abu Bakra Radi-Allahu ‘anhu: Allah’s Apostle (Sallallahu ‘Alaihi Wa ‘Aalehi Wa Sallam) said thrice, “Shall I not inform you of the biggest of the great sins?” We said, “Yes, O Allah’s Apostle

(Sallallahu ‘Alaihi Wa ‘Aalehi Wa Sallam) ” He said, “To join partners in worship with Allah: to be undutiful to one’s parents.” The Prophet (Sallallahu ‘Alaihi Wa ‘Aalehi Wa Sallam) sat up after he had been reclining and added, “And I warn you against giving forged statement and a false witness; I warn you against giving a forged statement and a false witness.” The Prophet (Sallallahu ‘Alaihi Wa ‘Aalehi Wa Sallam) kept on saying that warning till we thought that he would not stop.