“Usfartem lachem… sheva shabatot temimot tihiyena”, you shall count seven complete weeks. The concept of “temimot”, complete, plays a central role in the halachik discussions on sefirat ha’omer.
The first and most definitive halacha learned from “temimot” is the proper time to count the omer. The Gemara Menachot (66a), after establishing that counting the omer commences with the harvesting of the omer offering, asks, “Could we say that the harvesting, counting and offering of the Omer is done in the day?” The answer offered is “it says ‘seven complete weeks’, when are there seven complete weeks, when you begin counting at night”. All poskim agree that the proper and ideal time for counting the omer is at nightfall; when one does not count immediately he may count at any time throughout the night (Shulchan Aruch OC 489/1).
The halacha of counting at night leads to several other discussions. Firstly, we find differing opinions amongst the poskim as to whether one can count during the day if he did not count at night. While the Bahag (Rav Shimon Kayra author of Halachot Gedolot) and the Meiri are of the opinion that when necessary one may count during the day, Rabeinu Tam and others reject the possibility of counting during the day. In the Shulchan Aruch, we find that one who did not count at night should count during the day but refrain from reciting a beracha . The Magen Avraham explains that counting during the day constitutes a fault in temimot and, therefore, the beracha is not recited.
Other extensions of the halacha to count at night are questions of what should be done if the public is counting after sunset but before nightfall or if one counted by mistake after sunset.
“Temimot” also pertains to the question of what a person who forgot to count one day should do. The Bahag is of the opinion that temimot requires counting all the days. When one day is missed, the count is incomplete and becomes invalid. The Tosefot rejects this idea and as expressed by the Rosh considers each day an independent mitzvah validating the continued count even when a day has been missed.
This debate of whether “temimot” requires a valid continuous count of all the days raises some interesting discussions. One such discussion concerns a boy who turns thirteen during sefirat ha’omer. Even if he has counted all the days up to the date of his Bar Mitzvah, they were not counted by a person whom we consider incumbent in the mitzvah. Can and should we view this young man, who actually counted the days and weeks, as having fulfilled the mitzvah and to whom, therefore, temimot applies? Or, do we say that since the first days were not counted as a required mitzvah they do not blend with the later days to constitute a complete counting?
Similarly, a question is raised in reference to a convert. If we require temimot, a complete count of fifty days, the convert who has not previously counted cannot fulfill the mitzvah of counting the omer for that year. On the other hand, if we see each day as independent we must require the convert to count the remaining days.
A third area where “temimot” is applied pertains to when Shavuot begins. In an introduction to his comments on Shulchan Aruch Orach Chayim 494, the Taz (Turei Zahav – Rav David Halevi 1586-1667) writes “Tefila is delayed on Shavuot night so that the sefira will be complete”. In a similar fashion the Magen Avraham (Rav Avraham Gumbiner 1637-1683) writes “Kidush on the night of Shavuot should not be made until tzeit hakochvim, nightfall, since it is said ‘temimot tihiyena’, and they shall be complete”. The rationale guiding these and other poskim is that accepting the sanctity of Yom Tov incorporates the remainder of the day into Shavuot rendering the last day of sefira incomplete.
Some poskim note that the Magen Avraham seems a bit more lenient allowing Tefila to be said before nightfall but prohibiting the official declaration of kidush. Rav Ovadya Yosef (Ychave Daat vol.6 res. 30) notes that there are other poskim such as Rav Yaakov Emdin (in his siddur Beit Yaakov) who are even more lenient and do not apply the principle of temimot to the time Shavuot should begin. Rav Yosef suggests that places such as Israel (and all the more so countries in the Southern Hemisphere-M.A.) follow the more stringent opinions of the Taz and Magen Avraham and only in Northern countries, where nightfall at that time of year is so late, should a greater leniency be allowed.