Charles Ellicott 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)

Shall not go up. —The enemy, on the same battlefield, would have prepared for attack from the same direction as before; consequently, David is directed to go around them and attack them unexpectedly from the opposite direction.