John Gill Commentary 1 Samuel 25:20

"And it was so, as she rode on her ass, and came down by the covert of the mountain, that, behold, David and his men came down toward her; and she met them." — 1 Samuel 25:20 (ASV)

And it was [so, as] she rode on the ass
After her servants:

that she came down, by the covert of the hill ;
by the side of it, which was covered with bushes, and she rode among them, in a way that led through them, and so was not seen by David and his men; or by the shadow of the hill, toward the bottom of it, where by reason of that, and the opposite hill, it was darkish, and they could not see each other:

and, behold, David and his men came down against her ;
came down a hill opposite to that she came down:

and she met them ;
in the valley between two hills.