At a second and a third distance of a thousand cubits the same process was repeated when the waters were found to be first waters to the knees, and secondly waters to (or, of) the loins. The unusual expression, מַיִם בִּרְכָּים, instead מֵי, as in the similar expressions before and after, may have been chosen, Keil suggests, in order to avoid resemblance to the phrase, מֵימֵי רַגְלַיִם in Isaiah 36:12 (Keri)—not a likely explanation.
Havernick describes it simply as an instance of bold emphasis. Schroder breaks it up into two clauses, thus: "waters, to the knees they reach." Smend changes מַיִם into מֵי.