Among the sins that Nabiy (sallallahu ‘alayhi wasallam) highlighted, pinpointed and cautioned the Ummah about is indulging in interest/Riba. This prohibition is mentioned in the Holy Quran and the Hadith. There are warnings for those taking, giving and witnessing transactions of interest (riba).
Here is a talk delivered by my beloved father, Moulana Haroon Abasoomar (rahimahullah) on the topic of Riba (interest)
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