Rashi on Deuteronomy 29:11/רש"י על דברים כ״ט:י״א

1לעברך means THAT THOU SHOULDEST PASS [INTO THE COVENANT]. It would not, however, be correct to explain it as meaning “to make thee pass” (when the suffix would be objective), but it must be explained like (Deuteronomy 4:14) לעשתכם אתם, “that ye may do them”.

2לעברך בברית THAT THOU SHOULDEST PASS INTO THE COVENANT — The way of “passing” was as follows: those who made a covenant used to make a partition (i.e. used to place objects in a straight line) on one side and a partition on the other and passed between them, as it is said, (Jeremiah 34:18—20) “[And I will give the men which have not performed the words of the covenant which they made before Me] when they cut the calf in two, and passed between the parts thereof … [into the hands of their enemies]”.