c. 210–220 · Tertullian, On Fasting (De ieiunio adversus psychicos) 6
On the other hand, he whose “heart” was habitually found “lifted up” rather than fattened up, who in forty days and as many nights maintained a fast above the power of human nature, while spiritual faith subministered strength (to his body), both saw with his eyes God’s glory, and heard with his ears God’s voice, and understood with his heart God’s law: while He taught him even then (by experience) that man liveth not upon bread alone, but upon every word of God; in that the People, though fatter than he, could not constantly contemplate even Moses himself, fed as he had been upon God, nor his leanness, sated as it had been with His glory! Deservedly, therefore, even while in the flesh, did the Lord show Himself to him, the colleague of His own fasts, no less than to Elijah. For Elijah withal had, by this fact primarily, that he had imprecated a famine, already sufficiently devoted himself to fasts: “The Lord liveth,” he said, “before whom I am standing in His sight, if there shall be dew in these years, and rain-shower.” Subsequently, fleeing from threatening Jezebel, after one single (meal of) food and drink, which he had found on being awakened by an angel, he too himself, in a space of forty days and nights, his belly empty, his mouth dry, arrived at Mount Horeb; where, when he had made a cave his inn, with how familiar a meeting with God was he received!