1 Samuel 17:37-39

Amplified Bible

³⁷ David said, “The Lord who rescued me from the paw of the lion and from the paw of the bear, He will rescue me from the hand of this Philistine.” And Saul said to David, “Go, and may the Lord be with you.” ³⁸ Then Saul dressed David in his garments and put a bronze helmet on his head, and put a coat of mail (armor) on him. ³⁹ Then David fastened his sword over his armor and tried to walk, [but he could not,] because he was not used to them. And David said to Saul, “I cannot go with these, because I am not used to them.” So David took them off.