The mulberry trees - Rather, the Bacah-tree, and found abundantly near Mecca. It is very like the balsam-tree, and probably derives its name from the exudation of the sap in drops like tears when a leaf is torn off. Some think the valley of Baca Psalm 84:6 was so called from this plant growing there.

Fetch a compass behind them - When they may be had, God will not work without using human means. By this he taught David caution, prudence, and dependence on the Divine strength.

And when David inquired of the Lord,.... For though he had success before, and got the victory, he would not engage again with them without having the mind and will of God, on whom he knew victory alone depended:

he said, thou shalt not go up; that is, directly, and in a straight line:

but fetch a compass behind them; and get to the rear of them, instead of falling upon them in the front:

and come upon them over against the mulberry trees: which grew in the valley of Rephaim, and near where the Philistines had pitched.

David inquired once more of the Lord what he was to do, and received this answer: "Thou shalt not go up (i.e., advance to meet the foe, and attack them in front); turn round behind them, and come upon them (attack them) opposite to the Baca-shrubs." בּכאים, a word which only occurs here and in the parallel passage in 1 Chronicles 14:14, is rendered ἀπίους, pear-trees, by the lxx, and mulberry-trees by the Rabbins. But these are both of them uncertain conjectures. Baca, according to Abulfadl, is the name given in Arabic to a shrub which grows at Mecca and resembles the balsam, except that it has longer leaves and larger and rounder fruit, and from which, if a leaf be broken off, there flows a white pungent sap, like a white tear, which is all probability gave rise to the name בּכא equals בּכה, to weep (vid., Celsii, Hierob. i. pp. 338ff., and Gesenius, Thes. p. 205).

And when David inquired of the LORD, he said, Thou shalt not go up; but fetch a compass behind them, and come upon them over against the mulberry trees.

5:23 Go up - Directly against them, as the following words explain it. Behind - Where they least expect thee; God's purposes and promises do not exclude men's endeavours.

5:17-25 The Philistines considered not that David had the presence of God with him, which Saul had forfeited and lost. The kingdom of the Messiah, as soon as it was set up in the world, was thus attacked by the powers of darkness. The heathen raged, and the kings of the earth set themselves to oppose it; but all in vain, Ps 2:1, &c. The destruction will turn, as this did, upon Satan's own kingdom. David owns dependence on God for victory; and refers himself to the good pleasure of God, Wilt thou do it? The assurance God has given us of victory over our spiritual enemies, should encourage us in our spiritual conflicts. David waited till God moved; he stirred then, but not till then. He was trained up in dependence on God and his providence. God performed his promise, and David failed not to improve his advantages. When the kingdom of the Messiah was to be set up, the apostles, who were to beat down the devil's kingdom, must not attempt any thing till they received the promise of the Spirit; who came with a sound from heaven, as of a rushing, mighty wind, Ac 2:2.