It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:
"There are seventy degrees of usury, the least of which is equivalent to a man having intercourse with his mother." (DE)
English reference (DE): Vol. 3, Book 12, Hadith 2274 (DE)
Arabic reference (DE): Book 12, Hadith 2360 (DE)