1 Samuel 18:1-4

After David had finished talking with Saul, Jonathan became one in spirit with David, and he loved him as himself. From that day Saul kept David with him and did not let him return home to his family. And Jonathan made a covenant with David because he loved him as himself. Jonathan took off the robe he was wearing and gave it to David, along with his tunic, and even his sword, his bow and his belt.