And if you do not do it, then take a notice of war from Allâh and His Messenger but if you repent, you shall have your capital sums. Deal not unjustly (by asking more than your capital sums), and you shall not be dealt with unjustly (by receiving less than your capital sums).
Narrated by: Abu Huraira
A man demanded his debts from Allah's Apostle in such a rude manner that the companions of the Prophet intended to harm him, but the Prophet said, "Leave him, no doubt, for he (the creditor) has the right to demand it (harshly). Buy a camel and give it to him." They said, "The camel that is available is older than the camel he demands. "The Prophet said, "Buy it and give it to him, for the best among you are those who repay their debts handsomely. "