1 Samuel 20:42
And Jonathan said to David, Go in peace, forasmuch as we have sworn both of us in the name of the LORD, saying, The LORD be between me and thee, and between my seed and thy seed for ever. And he arose and departed: and Jonathan went into the city.
The verse records the parting of Jonathan and David, with David departing as a fugitive from Saul while Jonathan returns to the city, sending him away in peace. The farewell renews an oath sworn in the name of the Lord that the two men would remain loyal to each other and that the bond would continue between their descendants forever. The covenant united them as brethren in a most sacred union, with Jonathan's soul knit to David's soul and loving him as his own soul, their hearts knit together. In that covenant Jonathan stripped himself of the robe upon him and gave it to David, together with his garments, his sword, his bow, and his girdle.
The bond of union between their hearts remained unbroken until the deaths of Saul and Jonathan. The friendship was the Lord's doing and providence to preserve David's life as the future ruler of Israel when Saul would try to kill him, with Jonathan made the means of preserving him. God's providence connected David with Saul so that by wise behavior David would gain the confidence of the people, and by a long course of hardships and vicissitudes would be led to put entire trust in God while being prepared to become ruler of His people.