1 Samuel 17:38-39 NIV

38 Then Saul dressed David in his own1 tunic. He put a coat of armor on him and a bronze helmet on his head.

References for 1 Samuel 17:38

39 David fastened on his sword over the tunic and tried walking around, because he was not used to them. "I cannot go in these," he said to Saul, "because I am not used to them." So he took them off.