Much of Parashat Re’ei is devoted to the concept of “ha-makom asher yivchar Hashem” – a phrase that is repeated numerous times in this parasha, and refers to the special location in Eretz Yisrael that God would later designate as the exclusive site of sacrificial offerings. Of course, this was the Beit Ha-mikdash which was built in Jerusalem. Moshe in this parasha tells Benei Yisrael that whereas currently they were allowed to sacrifice anywhere, upon entering the Land of Israel, God would designate a specific site, and “le-shikhno tidreshu u-vata shama” – they were to go there, to the site of the Shekhina, to offer their sacrifices (12:5). The Rambam, in the opening passage of Hilkhot Melakhim, cites this verse as the source for the Biblical obligation to build a Mikdash.
Many later writers have noted the seeming discrepancy between the Rambam’s comments here in Hilkhot Melakhim and elsewhere – the beginning of Hilkhot Beit Ha-bechira, and in Sefer Ha-mitzvot (asei 20) – where he cites a different source for this obligation (“Ve-asu li Mikdash” – Shemot 25:8). Leaving aside this question, it is worth nothing the significance of the Rambam’s citation in Hilkhot Melakhim. If, indeed, the command, “le-shikhno tidreshu u-vata shemo” marks the source of the obligation to construct a Mikdash, then, conceivably, it also informs the essence and definition of this mitzva. Namely, the mitzva is about the notion of “derisha,” of actively seeking out God and working to build a relationship with Him. The verses here in Parashat Re’ei emphasize the fundamental difference between the service of God in the Temple and the pagan nations’ worship of their deities, which occurred “on the high mountains, on the hills, and under every lush tree” (12:2). The pagans designated many different locations as sites for ritual worship, such that one did not have to go far to offer a sacrifice. In direct contrast, the Torah commands, “le-shikhnu tidreshu.” The mitzva to build a Mikdash is a command of “derisha,” of leaving the comfort of one’s current location and circumstances and making a concentrated effort to forge a meaningful relationship with God. This verse is the source of the mitzva to construct a Temple because this obligation is rooted in the need for “derisha,” for work and effort in the service of God. The very notion of a location designated as the exclusive site for sacrifice teaches us this lesson of “derisha,” that we cannot possibly expect or hope to build a connection with the Almighty without inconveniencing ourselves and without investing time and hard work in this lofty goal.