أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِنَّ الْمَلاَئِكَةَ تُصَلِّي عَلَى أَحَدِكُمْ مَا دَامَ فِي مُصَلاَّهُ الَّذِي صَلَّى فِيهِ مَا لَمْ يُحْدِثِ اللَّهُمَّ اغْفِرْ لَهُ اللَّهُمَّ ارْحَمْهُ " .
It was narrated from Abu Hurairah that the Messenger of Allah (PBUH) said: "The angels send Salah upon any one of you so long as he is in the place where he prays, and so long as he does not invalidate his ablution, (saying): 'O Allah, forgive him, O Allah, have mercy on him.'" Translation Not Available
Book Ref: Sunan An Nisai Book 8 Hadith 733
Web Ref: Sunan An Nisai Vol 1 Book 8 Hadith 734