Musnad Abu Ya'la al-Mawsili 2:44

Ubayd Allah ibn Umar narrated to us, Ghundar Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Simak ibn Harb, who said: I heard al-Nu'man ibn Bashir delivering a sermon. He said: Umar ibn al-Khattab mentioned what the people had attained of the world, and he said: "I have indeed seen the Messenger of Allah (may Allah bless him and grant him peace) spend the day twisting [in hunger], not finding even poor-quality dates to fill his stomach."