Question: What if one forgot to count Sefirah Thursday night and didn’t remember until Friday eve after accepting Shabbat early? May he count at that point before it turns dark and then continue saying the berachah for the Omer the next evening?
Answer: Your scenario is precisely the reason why some are reluctant to take in Shabbat early during Sefirah. Of course, many do so because they have young children whom they wish to include in the Friday night se’udah or because they simply cannot eat late and properly digest their food.
HaGaon Rabbi Moshe Feinstein (Igrot Moshe, Orach Chayim, vol. 4, 99:3) rules that in the scenario you presented, one may indeed count for the previous night and continue saying a berachah on subsequent nights.
We find the following regarding a niddah in Parshat Metzora (Leviticus 15:28), “Ve’im tohara mizovah ve’safra lah shiv’at yomim ve’achar tit’har – If she ceases her flow, she must count for herself seven days and after that she can be purified.”
According to the Rema (Yoreh De’ah 196:11), she begins to count the seven days only following an interval of five full days, after which she checks and dons “whites.” Now, what if the evening that the woman is supposed to don “whites” and begin the count is a Friday night and her congregation recited Maariv early? Can she begin counting at shekiah (sundown) or did the early Maariv cut into her five days of 24 hours so that she must now wait until Motza’ei Shabbat to begin counting?
The Rema (infra, Yoreh De’ah 196:1) cites two views. The Terumat HaDeshen says she must wait until Motza’ei Shabbat, while the Agur (in the name of Maharil) says she does not wait. The Rema writes that our custom is to follow the Terumat HaDeshen, but post facto the Agur can be relied on.
The Taz connects this machlokes to Sefirat HaOmer. In support of the Agur’s view, the Taz notes that even if Maariv is davened early, Sefirat HaOmer cannot take place until nightfall, even on Friday night on which one is fulfilling the biblical precept of tosefet Shabbat by davening early.
The Taz obviously took a cue from Tosafot (Ketubbot 72a, s.v. “Ve’safra lah, le’atzmah”) who asks the following: If the Torah required her to count, why doesn’t she say a blessing on this mitzvah just as one says a blessing when counting the Omer? In regard to Sefirat HaOmer, the Torah says “u’sfartem – you shall count” and in regards to niddah the Torah states “ve’safra – she shall count.”
Tosafot answers that a niddah’s count may be overturned. Thus, she doesn’t count with a berachah.
In any event, we see that a comparison is drawn between Sefirat HaOmer and Sefirat HaNiddah, and what applies to one counting generally applies to the other. So the counting for both should begin at nightfall.
However, the Mechaber states (Orach Chayim 489:3): “If an individual prayed [Ma’ariv] with the congregation while it’s yet day, he counts with them without a blessing, and if he remembers at night he counts [again] with a blessing.” The Rema adds that even if he answered Amen to the blessing uttered at Maariv, he repeats the count with a blessing if he intended earlier not to discharge his obligation.
The Taz (ad loc.) takes issue with the Mechaber’s ruling. He asks: Is our discussion about wicked desecrators who violate the rules of Sefirat HaOmer and count while it’s yet day? He concludes that the Mechaber must be talking about the period of bein ha’shemashot, which might be night.
At the end of his discussion on this matter, Rabbi Feinstein posits that it’s more reasonable to conclude like those who require one to count after shekiah even though Maariv may be prayed at the earlier time, immediately after (plag haminchah). Thus, one may still count the Omer of the previous evening after one’s congregation has prayed an early Maariv. And after shekiah, one may count for that evening and continue to count every subsequent evening with a blessing.
May we merit the coming of Moshiach so that we may not only fulfill the mitzvah of counting the Omer but merit to actually bring the Omer to the third Beit HaMikdash.