Reference
ID 6618
Collector Muslim ibn al-Hajjaj
Book Sahih Muslim
Chapter The Book Pertaining to the Remembrance of Allah; Supplication; Repentance and Seeking Forgiveness
Reference (English Book) Book 35, Hadith 6588
Reference (Arabic Book) Book 49, Hadith 7103
Hadith Type Khabar
Matn (English)

Abu Dharr reported that Allah's Messenger (may peace be upon him) said: There is no believing servant who supplicates for his brother behind his back (in his absence) that the Angels do not say: The same be for you too.

Matn (Arabic)

حَدَّثَنِي أَحْمَدُ بْنُ عُمَرَ بْنِ حَفْصٍ الْوَكِيعِيُّ، حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، حَدَّثَنَا أَبِي، عَنْ طَلْحَةَ بْنِ عُبَيْدِ اللَّهِ بْنِ كَرِيزٍ، عَنْ أُمِّ الدَّرْدَاءِ، عَنْ أَبِي الدَّرْدَاءِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ مَا مِنْ عَبْدٍ مُسْلِمٍ يَدْعُو لأَخِيهِ بِظَهْرِ الْغَيْبِ إِلاَّ قَالَ الْمَلَكُ وَلَكَ بِمِثْلٍ ‏"‏ ‏.‏