Sunan an-Nasa'i 4618
It was narrated that Abu Hurairah said:
"A man had lent a camel of a certain age to the Prophet and he came to get it back. He said: "Give it to him" But they could only find a camel that was older than it. He said: "Give it to him." He said: "You have repaid me well," The Messenger of Allah said; "The best of you is the one who is best in repaying"
أَخْبَرَنَا عَمْرُو بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ سَلَمَةَ بْنِ كُهَيْلٍ، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ كَانَ لِرَجُلٍ عَلَى النَّبِيِّ صلى الله عليه وسلم سِنٌّ مِنَ الإِبِلِ فَجَاءَ يَتَقَاضَاهُ فَقَالَ ‏"‏ أَعْطُوهُ ‏"‏ ‏.‏ فَلَمْ يَجِدُوا إِلاَّ سِنًّا فَوْقَ سِنِّهِ قَالَ ‏"‏ أَعْطُوهُ ‏"‏ ‏.‏ فَقَالَ أَوْفَيْتَنِي ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِنَّ خِيَارَكُمْ أَحْسَنُكُمْ قَضَاءً ‏"‏ ‏.‏