Musannaf Ibn Abi Shayba 13:3048

Abu Bakr narrated to us, he said: Ghundar narrated to us, from Shu'bah, from Abu al-Fayd, he said: I heard Abdullah ibn Yasar say: I saw Abu al-Darda' bargaining with a man, and he (the man) swore that he would not sell it to him. Then, after that, he gave it to him for that price. Abu al-Darda' said: "I fear and I dislike that I should cause you to commit a sin."