Maliks Muwatta Book 31, Hadith Number 83.

Section : Usury in Debts.

Yahya related to me from Malik from Uthman ibn Hafs ibn Khalda from Ibn Shihab from Salim ibn Abdullah that Abdullah ibn Umar was asked about a man who took a loan from another man for a set term. The creditor reduced the debt, and the man paid it immediately Abdullah ibn Umar disliked that, and forbade it.