Musnad Ahmad 2:54

Abu Sa’id, the freed slave of Banu Hashim, narrated to us, saying: Al-Haytham ibn Rafi’ al-Tatari, a Basran, narrated to us, saying: Abu Yahya, a man from the people of Makkah, narrated to me, from Farrukh, the freed slave of ‘Uthman: That ‘Umar—and he was the Commander of the Faithful on that day—went out to the mosque and saw food scattered. He said, "What is this food?" They said, "Food that was brought to us." He said, "May Allah bless it and bless the one who brought it." It was said, "O Commander of the Faithful, it has been hoarded." He said, "And who hoarded it?" They said, "Farrukh, the freed slave of ‘Uthman, and so-and-so, the freed slave of ‘Umar." So he sent for them and summoned them. He said, "What compelled you to hoard the food of the Muslims?" They said, "O Commander of the Faithful, we buy with our wealth and we sell." ‘Umar said, "I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever hoards food from the Muslims, Allah will strike him with bankruptcy or leprosy.'" Upon that, Farrukh said, "O Commander of the Faithful, I make a covenant with Allah and I make a covenant with you that I will never hoard food again." As for the freed slave of ‘Umar, he said, "We only buy with our wealth and sell." Abu Yahya said: I indeed saw the freed slave of ‘Umar afflicted with leprosy.