Musnad Ahmad 32:2027

'Abdullah narrated to us, 'Ubaydullah ibn Mu'adh narrated to me, my father narrated to us, Shu'bah narrated to us, from Qatadah and Humayd, from Anas, who said: "Hail fell upon us while Abu Talhah was fasting, and he began to eat from it. It was said to him: 'Do you eat while you are fasting?' He said: 'This is only a blessing.'"