Abdullah ibn Amr reported: They mentioned a man in front of the Messenger of Allah, peace and blessings be upon him, and they said, “He only eats if he is fed! He only moves if he is made to move!” The Prophet said, “You have backbitten him.” They said, “We only said what is true about him.” The Prophet said, “It is enough sin to mention bad things about your brother.”
In another narration, the Prophet said, “If what you said about him were not true, you would have slandered him.”
Source: Musnad ‘Abd Allāh ibn al-Mubārak 2
Grade: Hasan (fair) according to Al-Mundhiri
عَنْ عبد الله بن عمرو أَنَّهُمْ ذَكَرُوا عِنْدَ َرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ رَجُلا فَقَالُوا لا يَأْكُلُ حَتَّى يُطْعَمَ وَلا يَرْحَلَ حَتَّى يُرْحَلَ لَهُ فَقَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ اغْتَبْتُمُوهُ فَقَالُوا إِنَّمَا حَدَّثَنَا مَا فِيهِ قَالَ فَحَسْبُكَ إِذَا ذَكَرْتَ أَخَاكَ بِمَا فِيهِ
وفي رواية أخرى قال إِنْ قُلْتُمْ مَا لَيْسَ فِيهِ فَقَدْ بَهَتُّمُوهُ
2 مسند عبد الله بن المبارك
4/9 المحدث المنذري خلاصة حكم المحدث إسناده حسن في الترغيب والترهيب