The Prophet ﷺ borrowed a young camel from a man and said, "When the camels of zakat arrive, we will repay you."When they arrived, he said, "Abu Rafi, repay this man his young camel."I could not find anything except a camel six years old or older, so I informed the Prophet ﷺ.He said, "Give it to him, for the best of people are those who are best in repaying."
حدثنا هشام بن عمار حدثنا مسلم بن خالد حدثنا زيد بن أسلم عن عطاء بن يسار
أن النبي ﷺ استسلف من رجل بكرا وقال إذا جاءت إبل الصدقة قضيناك فلما قدمت قال يا أبا رافع اقض هذا الرجل بكره فلم أجد إلا رباعيا فصاعدا فأخبرت النبي ﷺ فقال أعطه فإن خير الناس أحسنهم قضاء
Reported by Muslim, Musaqat, chapter on the permissibility of borrowing animals and the recommendation of repaying with something better than what was owed, hadith no. 1600, from the hadith of Zayd, with slight variation.