1 Samuel 20:36

he said unto his lad, Run, find out now the arrows which I shoot--The direction given aloud to the attendant was the signal preconcerted with David. It implied danger.

Here is, 1. Jonathan's faithful performance of his promise to give David notice of the success of his dangerous experiment. He went at the time and to the place appointed (Sa1 20:35), within sight of which he knew David lay hid, sent his footboy to fetch his arrows, which he would shoot at random (Sa1 20:36), and gave David the fatal signal by shooting an arrow beyond the lad (Sa1 20:37): Is not the arrow beyond thee? That word [beyond] David knew the meaning of better than the lad. Jonathan dismissed the lad, who knew nothing of the matter, and, finding the coast clear and no danger of a discovery, he presumed upon one minute's personal conversation with David after he had bidden him flee for his life. 2. The most sorrowful parting of these two friends, who, for aught that appears, never came together again but once, and that was by stealth in a wood, Sa1 23:16. (1.) David addressed himself to Jonathan with the reverence of a servant rather than the freedom of a friend: He fell on his face to the ground, and bowed himself three times, as one deeply sensible of his obligations to him for the good services he had done him. (2.) They took leave of each other with the greatest affection imaginable, with kisses and tears; they wept on each other's neck till David exceeded, Sa1 20:41. The separation of two such faithful friends was equally grievous to them both, but David's case was the more deplorable; for, when Jonathan was returning to his family and friends, David was leaving all his comforts, even those of God's sanctuary, and therefore his grief exceeded Jonathan's, or perhaps it was because his temper was more tender and his passions were stronger. (3.) They referred themselves to the covenant of friendship that was between them, both of them comforting themselves with this in this mournful separation: "We have sworn both of us in the name of the Lord, for ourselves and our heirs, that we and they will be faithful and kind to each other from generation to generation." Thus, while we are at home in the body and absent from the Lord, this is our comfort, that he has made with us an everlasting covenant.

Jonathan arose - in fierce anger - We should probably understand this rather of Jonathan's grief than of his anger, the latter clause explaining the former: for he was grieved for David. He was grieved for his father - he was grieved for his friend.

And he said unto his lad, run, find out now the arrows which I shoot,.... He no doubt told him the mark which he should shoot at, the stone Ezel, and bid him look out about that for them:

and as the lad ran; before he had got to the mark:

he shot an arrow beyond him: or it; beyond the lad, or beyond the mark he shot at; purposely shooting with great strength, that he might exceed, and thereby give notice to David how things stood, which was the sign agreed on.

The next morning Jonathan made David acquainted with what had occurred, by means of the sign agreed upon with David. The account of this, and of the meeting between Jonathan and David which followed, is given very concisely, only the main points being touched upon. In the morning (after what had occurred) Jonathan went to the field, דּוד למועד, either "at the time agreed upon with David," or "to the meeting with David," or perhaps better still, "according to the appointment (agreement) with David," and a small boy with him.
Sa1 20:36
To the latter he said, namely as soon as they had come to the field, Run, get the arrows which I shoot. The boy ran, and he shot off the arrows, "to go out beyond him," i.e., so that the arrows flew farther than the boy had run. The form חצי for חץ only occurs in connection with disjunctive accents; beside the present chapter (Sa1 20:36, Sa1 20:37, Sa1 20:38, Chethibh) we find it again in Kg2 9:24. The singular is used here with indefinite generality, as the historian did not consider it necessary to mention expressly, after what he had previously written, that Jonathan shot off three arrows one after another.
Sa1 20:37-39
When the boy came to the place of the shot arrow (i.e., to the place to which the arrow had flown), Jonathan called after him, "See, the arrow is (lies) away from thee, farther off;" and again, "Quickly, haste, do not stand still," that he might not see David, who was somewhere near; and the boy picked up the arrow and came to his lord. The Chethibh החצי is evidently the original reading, and the singular is to be understood as in Sa1 20:37; the Keri החצּים is an emendation, according to the meaning of the words. The writer here introduces the remark in Sa1 20:39, that the boy knew nothing of what had been arranged between Jonathan and David.
Sa1 20:40
Jonathan then gave the boy his things (bow, arrows, and quiver), and sent him with them to the town, that he might be able to converse with David for a few seconds after his departure, and take leave of him unobserved.
Sa1 20:41
When the boy had gone, David rose (from his hiding-place) from the south side, fell down upon his face to the ground, and bowed three times (before Jonathan); they then kissed each other, and wept for one another, "till David wept strongly," i.e., to such a degree that David wept very loud. הנּגב מאצל, "from the side of the south," which is the expression used to describe David's hiding-place, according to its direction in relation to the place where Jonathan was standing, has not been correctly rendered by any of the early translators except Aquila and Jerome. In the Septuagint, the Chaldee, the Syriac, and the Arabic, the statement in Sa1 20:19 is repeated, simply because the translators could not see the force of הנּגב מאצל, although it is intelligible enough in relation to what follows, according to which David fled from thence southwards to Nob.
Sa1 20:42
All that is given of the conversation between the two friends is the parting word spoken by Jonathan to David: "Go in peace. What we two have sworn in the name of the Lord, saying, The Lord be between me and thee, and between my seed and thy seed for ever:" sc., let it stand, or let us abide by it. The clause contains an aposiopesis, which may be accounted for from Jonathan's deep emotion, and in which the apodosis may be gathered from the sense. For it is evident, from a comparison of Sa1 20:23, that the expression "for ever" must be understood as forming part of the oath. - Sa1 21:1. David then set out upon his journey, and Jonathan returned to the town. This verse ought, strictly speaking, to form the conclusion of 1 Samuel 20.
(Note: In our English version it does; but in the Hebrew, which is followed here, it forms the opening verse of Sa1 21:1-15. In the exposition of the following chapter it has been thought better to follow the numbering of the verses in our version rather than that of the original, although the latter is conformed to the Hebrew. - Tr.)
The subject to "arose" is David; not because Jonathan was the last one spoken of (Thenius), but because the following words, "and Jonathan came," etc., are in evident antithesis to "he arose and went."