Rabbi Shimon uses the analogy of the mother bird brooding over her chicks to show how Yisrael must count seven weeks and thereby draw down seven Sfirot.
779. And then the Holy One, blessed be He, draws down seven grades to that grade, NAMELY, MALCHUT, which unites with them, with those seven weeks, WHICH ARE THE SECRET OF CHESED, GVURAH, TIFERET, NETZACH, HOD, YESOD AND MALCHUT. And should you suggest that there are six grades, and no more, NAMELY CHESED, GVURAH, TIFERET, NETZACH, HOD AND YESOD, FOR MALCHUT IS THE ONE THAT RECEIVES FROM THEM AND IS NOT PART OF THE RECKONING, HE ANSWERS: Then mother, NAMELY, BINAH, is sitting upon the young, WHICH ARE CHESED, GVURAH, TIFERET, NETZACH, HOD, YESOD AND MALCHUT, and is to be found brooding over them. BINAH is sent to fly away FROM THEM, and we take those six young ones, NAMELY CHESED, GVURAH, TIFERET, NETZACH, HOD AND YESOD, with the grade that is below them, NAMELY, MALCHUT, to fulfill the verse: "but you shall surely let the mother go, and take the young to you" (Devarim 22:7), WHERE THE MOTHER IS BINAH AND THE YOUNG ARE CHESED, GVURAH, TIFERET, NETZACH, HOD, YESOD AND MALCHUT. AND WE THEREFORE COUNT SEVEN WEEKS, DRAWING DOWN SEVEN SFIROT, NAMELY, MALCHUT ALSO, AND HAVING DRAWN DOWN MALCHUT ALSO, WE DRAW DOWN CHESED, GVURAH, TIFERET NETZACH, HOD AND YESOD TO INCLUDE THEM IN MALCHUT.