David was anointed to the crown to take it out of Saul's hand, and over Jonathan's head, and yet here we find,
I. That Saul, who was now in possession of the crown, reposed a confidence in him, God so ordering it, that he might by his preferment at court be prepared for future service. Saul now took David home with him, and would not suffer him to return again to his retirement, Sa1 18:2. And David having signalized himself above the men of war, in taking up the challenge which they declined, Saul set him over the men of war (Sa1 18:5), not that he made him general (Abner was in that post), but perhaps captain of the life-guard; or, though he was youngest, he ordered him to have the precedency, in recompence of his great services. He employed him in the affairs of government; and David went out withersoever Saul sent him, showing himself as dutiful as he was bold and courageous. Those that hope to rule must first learn to obey. He had approved himself a dutiful son to Jesse his father, and now a dutiful servant to Saul his master; those that are good in one relation it is to be hoped will be so in another.
II. That Jonathan, who was heir to the crown, entered into covenant with him, God so ordering it, that David's way might be the clearer when his rival was his friend. 1. Jonathan conceived an extraordinary kindness and affection for him (Sa1 18:1): When he had made an end of speaking to Saul he fell perfectly in love with him. Whether it refers to his conference with Saul before the battle (Sa1 17:34, Sa1 17:37), or to that after (v. 51), in which it is probable much more was said than is there set down, is uncertain. But, in both, David expressed himself with so much prudence, modesty, and piety, such a felicity of expression, with so much boldness and yet so much sweetness, and all this so natural and unaffected, and the more surprising because of the disadvantages of his education and appearance, that the soul of Jonathan was immediately knit unto the soul of David. Jonathan had formerly set upon a Philistine army with the same faith and bravery with which David had now attacked a Philistine giant; so that there was between them a very near resemblance of affections, dispositions, and counsels, which made their spirits unite to easily, so quickly, so closely, that they seemed but as one soul in two bodies. None had so much reason to dislike David as Jonathan had, because he was to put him by the crown, yet none regards him more. Those that are governed in their love by principles of wisdom and grace will not suffer their affections to be alienated by any secular regards or considerations: the greater thoughts will swallow up and overrule the less. 2. He testified his love to David by a generous present he made him, Sa1 18:4. He was uneasy at seeing so great a soul, though lodged in so fair a body, yet disguised in the mean and despicable dress of a poor shepherd, and therefore takes care to put him speedily into the habit of a courtier (for he gave him a robe) and of a soldier, for he gave him, instead of his staff and sling, a sword and bow, and, instead of his shepherd's scrip, a girdle, either a belt or a sash; and, which made the present much more obliging, they were the same that he himself had worn, and (as a presage of what would follow) he stripped himself of them to dress David in them. Saul's would not fit him, but Jonathan's did. Their bodies were of a size, a circumstance which well agreed with the suitableness of their minds. When Saul put these marks of honour on David he put them off again, because he would first earn them and then wear them; but, now that he had given proofs of the spirit of a prince and a soldier, he was not ashamed to wear the habits of a prince and a soldier. David is seen in Jonathan's clothes, that all may take notice he is a Jonathan's second self. Our Lord Jesus has thus shown his love to us, that he stripped himself to clothe us, emptied himself to enrich us; nay, he did more than Jonathan, he clothed himself with our rags, whereas Jonathan did not put on David's. 3. He endeavored to perpetuate this friendship. So entirely satisfied were they in each other, even at the first interview, that they made a covenant with each other, Sa1 18:3. Their mutual affection was sincere; and he that bears an honest mind startles not at assurances. True love desires to be constant. Those who love Christ as their own souls will be willing to join themselves to him in an everlasting covenant.
III. That both court and country agree to bless him. It is but seldom that they agree in their favourites; yet David was accepted in the sight of all the people, and also (which was strange) in the sight of Saul's servants, Sa1 18:5. The former cordially loved him, the latter could not for shame but caress and compliment him. And it was certainly a great instance of the power of God's grace in David that he was able to bear all this respect and honour flowing in upon him on a sudden without being lifted up above measure. Those that climb so fast have need of good heads and good hearts. It is more difficult to know how to abound than how to be abased.

When he had made an end of speaking - These first five verses are omitted by the Septuagint. See the notes on the preceding chapter, 1 Samuel 17 (note).
Jonathan loved him as his own soul - The most intimate friendship subsisted between them; and they loved each other with pure hearts fervently. No love was lost between them; each was worthy of the other. They had a friendship which could not be affected with changes or chances, and which exemplified all that the ancients have said on the subject; Την φιλιαν ισοτητα ειναι, και μιαν ψυχην, τον φιλον ἑτερον αυτον; "Friendship produces an entire sameness; it is one soul in two bodies: a friend is another self."

And Saul took him that day,.... Not only into his favour, and into his service, but into his court; even on that very day he slew the Philistine, or however as soon as it could be done:

and would let him go no more home to his father's house; as he used to do before; when he only served as a musician to him, then he was only at court when Saul was in a melancholy disposition, and wanted him, and so was going and returning, and in the intervals kept his father's sheep, Sa1 17:15; but now he would not suffer him to attend such business any longer, since he was not only to become a courtier, and be made a prince or noble, but to marry his daughter, according to the declaration he had made, with respect to any man that should kill Goliath.

Saul would let him go no more home--He was established as a permanent resident at court.