Yahya related to me from Malik from Nafi that he heard Abdullah ibn Umar say, "If someone lends something, let the only condition be that it is repaid."
يَقُولُ مَنْ أَسْلَفَ سَلَفًا فَلاَ يَشْتَرِطْ إِلاَّ قَضَاءَهُ
Request/Fix translation
"مَنْ أَسْلَفَ في شَيءٍ فَلَا يَشْتَرط غَيرَ قَضَائِه".