The Torah in Parashat Pinchas presents the mitzva of the daily tamid sacrifice, which was offered each morning and afternoon in the Beit Ha-mikdash. One of the laws relevant to this sacrifice is that no sacrifices are offered in the Mikdash before the morning tamid or after the afternoon tamid. This halakha is inferred from a verse in Sefer Vayikra (6:5), in which the Torah commands that shelamim sacrifices should be offered on top of the tamid on the altar (“ve-hiktir aleha chelvei ha-shelamim”). The Gemara (Pesachim 59b) interprets this verse to mean “aleha hashleim kol ha-korbanot kulam” – all the sacrifices must be offered in between the two tamid sacrifices.
The Ramban, in his critique of the Rambam’s Sefer Ha-mitzvot, writes that this law constitutes one of the Torah’s affirmative commands, requiring offering all sacrifices after the morning tamid and before the afternoon tamid. The Rambam does not include this requirement in his list of the Torah’s commands, and the Ramban claimed that this omission is incorrect.
Rav Asher Weiss, in his Minchat Asher (Bamidbar, 60:3), observes that the Rambam and the Ramban likely argue about the fundamental nature of this halakha. The Rambam, it seems, viewed this halakha as a detail relevant to the offering of the daily tamid sacrifices. That is to say, the mitzva of the temidin is to offer one sacrifice that would precede all others, and a second at the end of the day which would be the final sacrifice offered. According to this perspective, the law of “aleha hashleim” does not constitute an independent requirement or prohibition, but is rather part of the definition of the tamid obligation. The Ramban, by contrast, understood that the obligation of temidin requires simply offering these two sacrifices each day during their respective time-frames, and then a separate Biblical command requires offering all other sacrifices in between the two temidin.
A practical difference between these two perspectives, as Rav Weiss notes, might be whether a sacrifice is valid post facto if it is offered before the morning tamid or after the afternoon tamid. This question is the subject of a lengthy discussion in Tosfos, in Masekhet Yoma (29a). If, as the Rambam likely maintained, the law of “aleha hashleim” should be seen as part of the definition of the tamid obligation, then there seems to be no reason to disqualify sacrifices offered before the morning tamid or afternoon tamid. According to this perspective, such offerings undermine the tamid sacrifices, but there is nothing inherently wrong with them. The only effect of offering these sacrifices at the improper time is that the tamid was not properly offered; these sacrifices, however, are perfectly valid. According to the Ramban, by contrast, it is certainly conceivable that such offerings would be disqualified after the fact. In his view, the law of “aleha hashleim” designates the time-frame for offering sacrifices. It relates not to the definition of the tamid obligation, but rather to the period within which any given sacrifice should be offered. It is thus quite conceivable that a sacrifice offered outside that time-frame is considered invalid.