The Shulchan Arukh (O.C. 489:2) writes that the “medakdekim” – meaning, those who are especially scrupulous in their halakhic observance – ensure not to count the omer until tzeit ha-kokhavim (nightfall), when the sky has darkened and night has definitely begun. The period between sunset and tzeit ha-kokhavim – known as “bein ha-shemashot” – is a time which we are uncertain whether to treat as day or night, and so the Shulchan Arukh rules that it is proper not to count the omer before tzeit ha-kokhavim, until we can be certain that night has fallen and the new halakhic day has begun. The Shulchan Arukh concludes, “ve-khein ra’ui la’asot” – “and this is indeed proper to do.” The clear implication of the Shulchan Arukh’s ruling is that strictly speaking, one may count the omer already during the period of bein ha-shemashot, despite the uncertainty involved, but it is preferable to wait until tzeit ha-kokhavim.
The ambivalence implied by the Shulchan Arukh surrounding this issue relates to an interesting debate among the Rishonim. Tosefot in Masekhet Menachot (66a, s.v. zekher) write that one may count the omer during the period of bein ha-shemashot, emphasizing, “and he does not have to wait until it is definitely night.” This formulation clearly suggests that Tosefot apply this ruling even le-khatechila (optimally). Meaning, according to Tosefot, not only has one fulfilled the mitzva after the fact if he counted the omer during bein ha-shemashot, but one may choose to do so from the outset, and does not have not wait until dark. The reason, Tosefot explain, is because of the famous rule of “safeik de-rabbanan le-hakel” – we may act leniently in regard to uncertainties involving a rabbinic obligation or prohibition. In the case of sefirat ha-omer, Tosefot maintain that the obligation to count the omer nowadays, in the absence of the Beit Ha-mikdash, applies only by force of rabbinic enactment, a view that represents the consensus among the Rishonim (the notable exception being the Rambam, who maintains that sefirat ha-omer constitutes a Biblical requirement even nowadays). Therefore, during bein ha-shemashot, one may rely on the possibility that night has already begun, such that he may already count the omer. Since the issue at stake is a rabbinic obligation, we may assume the lenient possibility, that the time for counting the omer has already set in. This is also the view of the Rosh (Pesachim 10:40).
The Ran (Pesachim 28a in the Rif), however, disagrees. He imposes a significant limitation on the rule of “safeik de-rabbanan le-hakel,” asserting that it does not apply “le-chatekhila.” This rule, according to the Ran, applies only after the fact, in situations where one performed the act and then a question arose as to whether or not the act satisfactorily fulfilled the rabbinic obligation. This is not to say that one may choose from the outset to rely on the lenient possibility and perform the act under questionable circumstances. In the Ran’s view, therefore, one must wait until tzeit ha-kokhavim before counting the omer, in order to avoid uncertainty. It is only if one mistakenly counted the omer during bein ha-shemashot that we may then apply the rule of “safeik de-rabbanan le-hakel” to absolve him of the need to count again after dark.
The Shulchan Arukh’s ruling (which is based on a responsum of the Rashba, 1:154) is a sort of compromise between these two opinions. Essentially, the Shulchan Arukh sides with Tosefot’s view, that one may choose from the outset to count during bein ha-shemashot, though he maintains that one should preferably endeavor to satisfy the stringent view of the Ran.
We will iy”H discuss this topic further tomorrow.