Chagigah 6B

ופרטות באהל מועד. ורבי עקיבא אומר: כללות ופרטות נאמרו בסיני, ונשנו באהל מועד, ונשתלשו בערבות מואב. ואי סלקא דעתך עולה שהקריבו ישראל במדבר ⁠— עולת תמיד הואי,

And the details of the mitzvot, e.g., the particulars of the sacrificial process, were said to Moses at a later time in the Tent of Meeting. And R' Akiva says: Both general statements and the details of mitzvot were said at Sinai and later repeated in the Tent of Meeting, and reiterated a third time by Moses to the Jewish people in the plains of Moab, as recorded in the book of Deuteronomy. And if it enters your mind to say that R' Yishmael holds that the burnt-offering that the Jewish people sacrificed in the desert at Mount Sinai was the daily burnt-offering, rather than the burnt-offering of an individual, the following question arises:

מי איכא מידי דמעיקרא לא בעי הפשט וניתוח, ולבסוף בעי הפשט וניתוח?!

Is there any offering that initially did not require skinning and cutting into pieces, as these details of the daily burnt-offering were transmitted later in the Tent of Meeting, and ultimately, when these details were added, the offering required skinning and cutting? It is not plausible that the details of a mitzva would change over time. Therefore, it is clear that according to the opinion of R' Yishmael the Jews did not sacrifice the daily burnt-offering before the giving of the Torah, which means that the burnt-offering sacrificed at Mount Sinai must have been a burnt-offering of appearance.

רבי אלעזר ⁠— דתניא: ״עולת תמיד העשויה בהר סיני״, רבי אלעזר אומר: מעשיה נאמרו בסיני, והיא עצמה לא קרבה.

The Talmud cites the source for the opinion of R' Elazar. As it is taught in a baraita: “It is a daily burnt-offering, which was performed on Mount Sinai” (Numbers 28:6). R' Elazar says: The details of its performance were said at Sinai, but it itself was not sacrificed until the Tabernacle was erected. This indicates that the offering brought on Mount Sinai was a burnt-offering of appearance.