(249) بَابُ إِذَا أَحَبَّ رَجُلا فَلا يُمَارِهِ ولا يَسْأَلُ عَنْهُ
Mu'adh ibn Jabal said, "When you have love for your brother, donot quarrel with him or treat him badly nor ask questions about him, Itmay be that an enemy of his will appear and say something about him whichis not true and will thereby cause a split between you."
Reference: Al-Adab Al-Mufrad 545
In-book reference: Book 30, Hadith 8
English translation: Book 30, Hadith 545