Hadith 17:243
Ubayd Allah ibn Musa narrated to us, he said: Hasan informed us, from Ata’ ibn al-Sa’ib, from al-Sha’bi, from Ibn Mas’ud, who said: If you say what is in him while he is listening, then you have backbitten him. And if you say what is not in him, then you have slandered him.
حدثنا عبيد الله بن موسى قال أخبرنا حسن عن عطاء بن السائب عن الشعبي عن بن مسعود قال إذا قلت ما هو فيه وهو يسمع فقد إغتبته وإذا قلت ما ليس فيه فقد بهته