1 Samuel 17:37-39 New American Bible (Revised Edition) (NABRE)
37 David continued: “The same Lord who delivered me from the claws of the lion and the bear will deliver me from the hand of this Philistine.” Saul answered David, “Go! the Lord will be with you.”
Preparation for the Encounter. 38 Then Saul dressed David in his own tunic, putting a bronze helmet on his head and arming him with a coat of mail. 39 David also fastened Saul’s sword over the tunic. He walked with difficulty, however, since he had never worn armor before. He said to Saul, “I cannot go in these, because I am not used to them.” So he took them off.