Musnad Ahmad 33:554

Hassan narrated to us, Ibn Lahi'ah narrated to us, Abu al-Zubayr narrated to us, from Jabir, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Our Lord, Mighty and Majestic is He, said: 'Fasting is a shield with which the servant protects himself from the Fire, and it is for Me, and I reward for it.'"