Bulugh al-Maram, Book 16, Hadith 1541 (English)

Ibn ’Abbas (RAA) narrated that the Messenger of Allah said: “Don’t dispute with your brother; don’t make jokes with him; and don’t make him a promise which you would break.” Related by At-Tirmidhi with a weak chain of narrators.

وَعَنْ اِبْنِ عَبَّاسٍ ‏-رَضِيَ اَللَّهُ عَنْهُمَا‏- قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ لَا تُمَارِ أَخَاكَ, وَلَا تُمَازِحْهُ, وَلَا تَعِدْهُ مَوْعِدًا فَتُخْلِفَهُ } أَخْرَجَهُ اَلتِّرْمِذِيُّ بِسَنَدٍ فِيهِ ضَعْفٌ.‏ (1961)‏.‏ ‏3 ‏- ضعيف.‏ رواه الترمذي (1995)‏ وفي سنده ليث بن أبي سليم.‏

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also referenced under: Book 16, Hadith 1498 (In-Book)