Thou compassest my path ... - Margin, “winnowest.” The Hebrew word - זרה zârâh - means properly “to scatter,” to cast loosely about - as the wind does dust; and then, to winnow - to wit, by throwing grain, when it is thrashed, up to the wind: Isaiah 30:24; Jeremiah 4:11; Ruth 3:2. Then it means “to winnow out;” that is, to winnow out all the chaff, and to leave all the grain - to save all that is valuable. So here it means that God, as it were, “sifted” him. Compare Isaiah 30:28; Amos 9:9; Luke 22:31. He scattered all that was chaff, or all that was valueless, and saw what there was that was real and substantial. When it is said that he did this in his “path and his lying down,” it is meant that he did it in every way; altogether; entirely.
And art acquainted with all my ways - All the paths that I tread; the whole course of my life. All that I do, in all places and at all times, is fully known to thee.