Deuteronomy 20:2-4

And when you draw near to the battle, the priest shall come forward and speak to the people and shall say to them, ‘Hear, O Israel, today you are drawing near for battle against your enemies: let not your heart faint. Do not fear or panic or be in dread of them, for the LORD your God is he who goes with you to fight for you against your enemies, to give you the victory.’