The Messenger of Allah ﷺ borrowed a young camel from a man, and when the man came to ask for repayment, the Prophet ﷺ said to one of his companions, "Go and buy him a young camel."The man went and returned, saying, "I could only find a fully grown camel of excellent quality."The Prophet ﷺ said, "Give it to him, for the best of the Muslims is the one who is best in repaying his debts."
أخبرنا عمرو بن علي قال حدثنا عبد الرحمن قال حدثنا مالك عن زيد بن أسلم عن عطاء بن يسار
أن رسول الله ﷺ استسلف من رجل بكرا فأتاه يتقاضاه بكره فقال لرجل انطلق فابتع له بكرا فأتاه فقال ما أصبت إلا بكرا رباعيا خيارا فقال أعطه فإن خير المسلمين أحسنهم قضاء
Muslim narrated it in the Book of Musaqah, Chapter on the Permissibility of Borrowing an Animal and the Recommendation of Repaying with Something Better Than What Is Owed, Hadith: 1600, from the hadith of Malik, with this wording. It is also in Al-Kubra, Hadith: 6210, and Muwatta (Yahya): 2/680.