Mishkat al-Masabih 2906 — The lender has the right to demand repayment

Abu Huraira told that a man demanded payment of a debt from God's Messenger in a most uncivil manner and his companions were vexed, but he said, “Leave him alone, for one who has a right is entitled to speak, and buy him a camel and give it to him." When they told him that all they could find was one of a more excellent age than the man was entitled to, he said, “Buy it and give him it, for the best person among you is he who discharges his debt in the best manner." (Bukhari and Muslim.)