Musnad Ahmad 33:577

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu al-Zubayr narrated to us, he heard Jabir ibn Abdullah saying: The wives of the Messenger of Allah (peace and blessings of Allah be upon him) asked him for maintenance, and he did not have anything with him, so they pressed him. Abu Bakr came to him and asked for permission to enter, but he was not given permission. Then Umar came to him and asked for permission to enter, but he was not given permission. Then they asked for permission after that, and he gave them permission. They found him sitting among them. Umar said to him: "O Messenger of Allah, the daughter of Zayd asked me for maintenance, so I struck her"—or something to that effect—and he intended by that to make him laugh. He laughed until his molars appeared, and he said: "By the One in Whose hand is my soul, nothing kept me [from you] except that." They both stood up to their daughters and took them by their hands, and they said: "Do you ask the Messenger of Allah (peace and blessings of Allah be upon him) for what he does not have?" The Messenger of Allah (peace and blessings of Allah be upon him) forbade them from [doing anything to] them. They said: "We will not return to it." At that point, the [verse of] choice was revealed.