I know Christ quoted scripture constantly, but I find it kind of fun to run into which scripture he was quoting. So we have
Deuteronomy 8:3 And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the Lord doth man live.
It is fun to ponder the scriptures knowing that the Savior pondered the same verses. Many of us think little of the old testament, but those were the very scriptures Christ studied and loved. When Christ said "It is written, Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God" he was not only quoting the Old Testament, he was also referring to it.