(O ye who believe!) the reference here is to the sons of 'Amr Ibn 'Umayr Ibn 'Awf al-Thaqafi, [and they were four brothers:] Mas'ud [Ibn 'Amr], Hubayb [Ibn 'Amr], 'Abd Yalayl [Ibn 'Amr] and Rabi'ah [Ibn 'Amr] (observe your duty to Allah) fear Allah regarding usury, (and give up what remaineth (due to you) from usury) leave that which the Banu Makhzum owe you of usury, (if ye are (in truth) believers) if you really believe in the prohibition of usury.