Musnad Ahmad 920:3

Abu Mu'awiyah narrated to us, from Abu Ishaq al-Shaybani, from Yazid ibn al-Asamm, from Ibn Abbas, who said: A man came to Umar asking him [for charity], and Umar began looking at his head once and at his feet another time, to see if he could perceive any signs of poverty upon him. Then Umar said to him: "How much wealth do you have?" He said: "Forty camels." Ibn Abbas said: So I said: "Allah and His Messenger have spoken the truth: 'If the son of Adam had two valleys of gold, he would seek a third, and nothing fills the belly of the son of Adam except dust, and Allah accepts the repentance of whoever repents.'" Umar said: "What is this?" I said: "This is how my father recited it to me." He said: "Then pass by us to him [Ubayy ibn Ka'b]." He said: So he came to my father and said: "What is this one saying?" My father said: "This is how the Messenger of Allah, peace and blessings of Allah be upon him, recited it to me." He said: "So did you confirm it?" He said: "Yes," so he confirmed it.