Leviticus 7:38

which the Lord commanded Mosheh in Mount Sinai, in the day that he commanded the sons of Israel to offer their oblations before the Lord in the tabernacle that he made unto him in the wilderness of Sinai.

to present their offerings to God in the Sinai Desert for they did not offer a sacrifice before they arrived at Mount Sinai. I have already shown you [comment on Exodus 17:15] that the altar that Moshe built on the occasion of ⊂ Amaleq’s defeat was situated at Ḥorev (i.e., Sinai). Israel remained there for ten days under a year, as it is written [Exodus 19:1 vs . Numbers 10:11]. Moreover, they did not bring burnt-offerings while they were in the wilderness (as the prophet said, “Did you bring me sacrifices and offerings for forty years in the wilderness?” [Amos 5:25]). The families of Israel also did not bring the Paschal sacrifice (except in Egypt, and a second time at Mount Sinai) because they had no flocks in the wilderness. Nor did they perform any circumcisions once they had left Mount Sinai; and the majority were uncircumcised when Joshua had them circumcised for the sake of the Paschal sacrifice [Joshua 5:3].

WHICH THE ETERNAL COMMANDED MOSES IN MOUNT SINAI. According to our Rabbis all the commandments were expressly told to Moses on Mount Sinai, in their general rules, their specific regulations and their minute details, and some of them were repeated in the Tent of Meeting. Thus [all] the commandments in the Book of Vayikra (Leviticus) [which is prefaced by the verse stating it was made known in the Tent of Meeting], are repetitions [of those said on Sinai, which is the sense of the verse before us]. By way of the plain meaning of Scripture, the meaning of the verse is:. Now according to the interpretation of the Rabbis mentioned above, the sense of the verse is that the laws of the offerings were commanded to Moses “in Mount Sinai,” and were repeated to him in the Tent of Meeting “in the wilderness of Sinai.” Ramban will now explain that according to the plain meaning of Scripture this verse speaks of two separate occasions: the offerings of the seven-day consecration of the priests were commanded to Moses “in Mount Sinai,” whilst the laws of the other offerings were given to Moses “in the wilderness of Sinai,” that is, in the Tabernacle. “Which the Eternal commanded Moses in Mount Sinai, and in the day that he commanded the children of Israel in the wilderness of Sinai to present their offerings unto the Eternal,” for He gave the commandment about the consecration-offerings [of the priests] in Mount Sinai, as also in the case of the burnt-offering and sin-offering [which were part of the consecration], and He commanded concerning the meal-offering, guilt-offering, and peace-offerings, in the wilderness of Sinai, in the Tent of Meeting.
It is possible that the expression in Mount Sinai means “in this place in front of Mount Sinai,” which is in the Tent of Meeting. Similarly, It is a continual burnt-offering, which was offered in Mount Sinai, does not mean on the mountain itself, for the continual burnt-offering [i.e., the Daily Whole-offering brought for all Israel] began only in the Tent of Meeting, as it is written, Now this is that which thou shalt offer upon the altar: two lambs of the first year day by day continually. So also: And they set forward from the Mount of the Eternal [which means “from before the Mount of the Eternal”]; ye have dwelt long enough in this mountain [which means “in front of this mountain”]. The sense of all these verses is that Israel had encamped …