Himad ibn Uthman narrated that once when he was with Imam Sadiq (a.s), one of their companions entered, and Imam Sadiq asked him: “Why has so and so complained to me about you?” He replied: “He is complaining because I have asked him to pay back what is mine.” Imam Sadiq said
“Did you not think that he might get upset if you do so. Have you not read God's words in: “Those who join together those things which God hath commanded to be joined, hold their Lord in awe, and fear the terrible reckoning.” [The Holy Quran: Ra'd 13:21] “Do they fear that God may oppress them? No. They fear that they be asked for their account of deeds. God called it “the terrible reckoning”, implying that it is bad to reckon with your brother.”