Jesus quoted Deuteronomy 8.3 to rebuke the devil when he tempted Him to turn stones into bread after fasting for 40 days. When tempted by the forces of darkness, we must quote Scripture as Jesus did. More important, we must remember that our only spiritual food is the Word of God. Increase your time spent reading and studying the Bible.
We are in a fierce spiritual war with the forces of darkness and we must be ready for battle every day. We do that by putting on the armor of God. Every day we must gird our loins with the Truth, put on the breastplate of righteousness, shod our feet with the gospel of peace, take up the shield of faith, put on the helmet of salvation and take up the sword of the Spirit (Ephesians 6.13-18).
Girding one’s loins with the Truth is: knowing Scripture. Shodding our feet with the gospel is learning how and sharing the gospel by quoting the basic salvation passages (Romans 3.23, Hebrews 9.27; Matthew 25.46; Romans 5.8; John 3.16; Romans 6.23; Ephesians 2.8-9; John 14.6; Acts 12.4; John 1.12).
Taking up the sword of the Spirit is: memorizing Scripture so you can quote it when tempted by the forces of darkness. And remember to pray without ceasing (1 Thessalonians 5.17).