Abu Bakra:
Allah's Messenger (ﷺ) said thrice, "Shall I not inform you of the biggest of the great sins?" We said, "Yes, O
Allah's Messenger (ﷺ)" He said, "To join partners in worship with Allah: to be undutiful to one's parents."
The Prophet (ﷺ) 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 kept on saying that warning till we thought that he would not stop.