أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنِ الأَعْمَشِ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَنِ اسْتَعَاذَ بِاللَّهِ فَأَعِيذُوهُ وَمَنْ سَأَلَكُمْ بِاللَّهِ فَأَعْطُوهُ وَمَنِ اسْتَجَارَ بِاللَّهِ فَأَجِيرُوهُ وَمَنْ آتَى إِلَيْكُمْ مَعْرُوفًا فَكَافِئُوهُ فَإِنْ لَمْ تَجِدُوا فَادْعُوا لَهُ حَتَّى تَعْلَمُوا أَنْ قَدْ كَافَأْتُمُوهُ ‏"‏ ‏.‏

It was narrated that Ibn 'Umar said: "The Messenger of Allah said: 'Whoever seeks refuge with (the name of) Allah, grant him refuge; whoever asks of you in (the name of) Allah, give him; whoever seeks protection with (the name of Allah, give him protection. Whoever does you a favor, then reciprocate, and if you cannot, then supplicate for him until you think that you have repaid him."' Translation Not Available

Book Ref: Sunan An Nisai Book 23 Hadith 2567
Web Ref:  Sunan An Nisai Vol 3 Book 23 Hadith 2568