Hadith.3999 - Imam (as) said: "A man came to Abu Ja'far Imam Muhammad ibn Ali Al-Baqir (as) and said: "I have inherited wealth, and I know that the one from whom I inherited it used to engage in usury. I am certain that there is usury in it, and this knowledge makes even the lawful portion unpleasant for me. I have asked the jurists of Iraq and Hijaz, and they said it is not permissible for me to consume it because of what it contains." Abu Ja'far Imam Muhammad ibn Ali Al-Baqir (as) said to him: "If you know that there is a specific portion of it that is usury and you know its rightful owners, then take your principal amount and return what is beyond that. But if it is mixed, then consume it with ease and satisfaction, for the wealth is yours. Avoid what its previous owner used to do. Indeed, the Messenger of Allah (swt) (may Allah (swt) bless him and his family) forgave what has passed of usury and prohibited what remains. So whoever was ignorant of it, his ignorance is excused until he becomes aware of it. Once he knows it is prohibited, it becomes forbidden for him, and punishment becomes obligatory upon him if he engages in it, just as it is obligatory upon one who consumes usury."