Al-Sha'bi relates "that Miqdad bin al-Aswad (may Allah be pleased with him) borrowed seven thousand from Sayyiduna Uthman bin Affan (may Allah be pleased with him). When he asked him to repay it, Miqdad (may Allah be pleased with him) said: It is only four thousand. So they took the matter to Sayyiduna Umar (may Allah be pleased with him). Uthman (may Allah be pleased with him) said: I lent him seven thousand. And Miqdad (may Allah be pleased with him) said: Will you swear that it is seven thousand? (Umar (may Allah be pleased with him)) said: You have spoken fairly. But Uthman (may Allah be pleased with him) refused to swear, so Umar (may Allah be pleased with him) said: Take whatever he gives you. Then he said: By Allah, besides whom there is no true god, it is indeed seven thousand. He said: Then what prevents you from swearing, when this night and this day (are witnesses)?"
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17693