Abu Huraira reported God’s Messenger as saying, "Usury has seventy parts, the least important being that a man should marry his mother.” Ibn Majah and Baihaqi, in <i>Shu'ab al-iman</i>

وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الرِّبَا سَبْعُونَ جُزْءًا أيسرها أَن الرجل أمه»