I Samuel 18:3

Jonathan made a covenant (i.e., a covenant of friendship) and (i.e., with) David, because he loved him as his soul.

In the course of the foregoing chapter we left David in triumph; now in this chapter we have, I. The improvement of his triumphs; he soon became, 1. Saul's constant attendant (Sa1 18:2). 2. Jonathan's covenant friend (Sa1 18:1, Sa1 18:3, Sa1 18:4). 3. The darling of his country (Sa1 18:5, Sa1 18:7, Sa1 18:16). II. The allays of his triumphs. This is the vanity that accompanies even a right work, that "for it a man is envied," Ecc 4:4. So David was by Saul. 1. He hated him, and sought to kill him himself (Sa1 18:8-11). 2. He feared him, and contrived how he might have some mischief done him (Sa1 18:12-17). He proposed to marry his daughter to him; but, [1.] cheated him of the eldest to provoke him (Sa1 18:19), and, [2.] Gave him the younger, upon conditions which would endanger his life (Sa1 18:20-25). But David performed his conditions bravely (Sa1 18:26, Sa1 18:27), and grew to be more and more esteemed (Sa1 18:28-30). Still David is rising, but (as all that aim at the crown of life must expect) he had a great deal of difficulty and opposition to grapple with.

18:3-4 Out of his love for David and recognition that God had chosen David to be Israel’s next king (see 20:13-17, 30-31; 23:17), Jonathan made a solemn pact of friendship with David. By giving David items that symbolized his official status as the king’s son and crown prince, Jonathan symbolically gave David his right of succession to the throne.