Sunan an-Nasa'i, Volume 3, Book 23, Hadith 2568 (DarusSalam) ⓘ

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."'

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 ‏" ‏ ‏.‏