John Gill Commentary 2 Samuel 5:23

"And when David inquired of Jehovah, he said, Thou shalt not go up: make a circuit behind them, and come upon them over against the mulberry-trees." — 2 Samuel 5:23 (ASV)

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, you shall 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.