Albert Barnes Commentary Psalms 56:6

"They gather themselves together, they hide themselves, They mark my steps, Even as they have waited for my soul." — Psalms 56:6 (ASV)

They gather themselves together - That is, they do not attack me singly, but they unite their forces; they combine against me.

They hide themselves - They lurk in ambush. They do not come upon me openly, but they conceal themselves in places where they cannot be seen, that they may spring upon me suddenly.

They mark my steps - They watch me whatever I do. They keep a spy upon me, so that I can never be sure that I am not observed.

When they wait for my soul - As they watch for my life; or, as they watch for opportunities to take away my life. I am never secure; I know not at what time, or in what manner, they may spring upon me. This would apply to David when he fled to Achish, king of Gath; when he was driven away by him; and when he was watched and pursued by Saul and his followers as he fled into the wilderness (1 Samuel 21:1–15; 1 Samuel 22).