A second question is raised regarding the obligation of women with respect to this mitzva. The Rambam writes (Hilkhot Temidin u-Musafin 7:24):
This mitzva is incumbent on every Jewish male in every place and at all times. Women and servants are absolved from it.
The Ramban in Kiddushin, in contrast, maintains that women are bound by this mitzva. What is his rationale? After all, it would seem that the Rambam is right, as sefirat ha-omer falls into the category of time-bound positive commandments, from which women are generally exempt!
Rav Soloveitchik suggests a single answer for the two questions. The mitzva that each individual performs has two aspects. One is the act of the mitzva; and the second is the count that is performed in order to build the foundation for the festival of Shavuot. The act of the mitzva is only at night, and therefore one who counts at night recites a blessing. One who forgot to count at night, counts during the day, but he only fulfills that aspect of the mitzva which is connected to Shavuot, and over this fulfillment no blessing is recited.
Based on this, we can explain the Ramban’s position that women are bound by this mitzva. While it is true that they are exempt from time-bound positive mitzvot, this is true regarding the act of the mitzva; however, the second aspect, whereby the people of Israel sanctify the festival of Shavuot, is not regarded a time-bound positive mitzva, and so it is incumbent upon women as well.
Based on a Shiur by
Harav Aharon Lichtenstein
Translated by David Strauss