من لا يحضره الفقيه, volume 3, page 275

Hadith.3995 - Ibrahim ibn Umar narrated from Abu Abdullah (as) regarding the saying of Allah (swt), the Almighty and Majestic: "And whatever you give as usury so that it may increase in the wealth of people, it does not increase with Allah (swt)" (Surah Ar-Rum 30:39) Imam (as) said: "It is your gift to a man through which you seek a better return than it, and that is consumed as usury."

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.

Hadith.3997 - Imam (as) said: "Any usury that people consumed out of ignorance, and then they repented, it will be accepted from them once their repentance is recognized." And Imam (as) said: "If a man inherits wealth from his father and knows that there is usury in that wealth, but it has been mixed with other lawful trade, then it is permissible and pure for him to consume it. However, if he identifies a specific portion as usury, he should take his principal amount and return the usury."

Translation: Bab Ul Qaim Publications — attributed by Thaqalayn·The Arabic above is the original.