Musnad Abu Ya'la al-Mawsili 3:242

Ubayd Allah ibn Umar narrated to us, Wahb ibn Jarir narrated to us, my father narrated to us, from Ibn Ishaq, from Yazid ibn Ruman al-Qurazi, from a man whom he named but I forgot, from Ali ibn Abi Talib, who said: I went out on a cold morning, hungry, and the cold had exhausted me. I took a woolen garment that we had, put it around my neck, and tied it over my chest to keep warm. By Allah, there was nothing in my house to eat, and if there had been anything in the house of the Prophet (peace be upon him), it would have reached me. I went out to some parts of Medina and headed toward a Jew in his garden. I looked at him through a gap in his wall. He said, "What is the matter with you, O Bedouin? Would you like a bucket for a date?" I said, "Yes, open the wall for me." He opened it for me, and I entered. I began to pull the bucket, and he would give me a date until I filled my palm. I said, "That is enough for me now." I ate them, then drank some water. Then I came to the Messenger of Allah (peace be upon him) and sat with him in the mosque while he was with a group of his companions. Mus’ab ibn Umayr appeared before us wearing a cloak patched with fur, and he had been the most pampered youth in Mecca and the most comfortable in life. When the Prophet (peace be upon him) saw him, he remembered the luxury he used to be in and saw the state he was in, so his eyes welled up and he wept. Then the Messenger of Allah (peace be upon him) said: "Are you better today, or [will you be better] when a tray of bread and meat is brought to one of you in the morning, and another is brought in the evening, and he goes out in one suit and returns in another, and you cover your houses just as the Kaaba is covered?" We said, "Rather, we are better on that day, as we will have free time for worship." He said, "Rather, you are better today."