The Prophet ﷺ said, "The worst form of usury is a person's transgression against the honor of his Muslim brother."
عن النبي ﷺ قال: أربى الربا استطالة المرء في عرض أخيه المسلم.
Abu Qasim Asbahani related it in Targheeb wa Tarheeb (588), from Ahmad bin Abdul-Rahman Dhakwani, who reported that Abu Bakr bin Mardawayh informed them, that Abu Bakr Muhammad bin Ishaq narrated to them, that Jafar bin Muhammad bin Hasan narrated to them, that Qutayba bin Saeed narrated to them, that Ibn Lahia narrated to them, from Abu Aswad, from Yahya bin Nadr, from Abu Hurairah, who mentioned it.Its chain of transmission is hasan because of Ibn Lahia, who has been criticized, but Qutayba bin Saeed's narration from him is sound.Abu Dawud (4877) also related it, by way of Amr bin Abu Salama, who said, Zuhayr narrated to us, from Ala bin Abdul-Rahman, from his father, from Abu Hurairah, with a similar wording.Amr bin Abu Salama was from Damascus, and Zuhayr is Ibn Muhammad Khurasani, and narrations of the people of Sham from him are not sound, and this is one of them.The hadith has other routes of transmission, weaker than this one.