Deuteronomy 12:8

It will not be lawful for you to do (there) as we do here today, whatever any one thinks fit for himself;

But you must not do as we are doing here After the death of Aaron — since they used to travel from one encampment to another — a man might offer, e.g., a burnt-offering, in whatever encampment he desired; or, one man might offer the firstborn of his flock, while another man did not so offer — because the obligation in each case is dependent on the land of Israel. I do not agree with this interpretation. Rather, Moshe’s meaning is that they were not all completely dedicated to God . The reason he can say we [thereby including even himself — Translator] is that there were many commandments concerning, e.g., burnt-offerings, which could not be fulfilled except in the land of Israel (for so it is written [Numbers 15: 2]).

YE SHALL NOT DO AFTER ALL THAT WE DO HERE THIS DAY, EVERY MAN WHATSOEVER IS RIGHT IN HIS OWN EYES. Rabbi Abraham ibn Ezra wrote by way of the plain meaning of Scripture, “they have explained it [as follows]: Because they were journeying from stage to stage, [they brought no offerings from the time they left Mount Sinai until after the death of Aaron in the fortieth year after the exodus. Even after his death] a person could bring an offering at any stage as he wished; there were some who gave the firstling of their flock [to the priest] and others who did not give, since the commandment [to give the firstborn] is dependent on the Land. [Hence the verse before us says that after arriving in the Land we are no longer to do whatever is right in the eyes of each individual.] But this is not my own opinion [continues Ibn Ezra]. Rather, the meaning of the verse is that they were not all G-d-fearing [and they sacrificed to the host of heaven; hence Moses warned them against continuing to do so in the Land of Israel]. And the reason Moses used the word ‘we’ [Ye shall not do after all that ‘we’ do — implying that he, too, participated in such transgressions] is because many commandments relating to the offerings apply only within the Land” [and not in the wilderness; hence, Moses himself had never fulfilled those commandments. He, therefore, included himself among the people]. This is Ibn Ezra’s language. But it is not correct, since it is out of context for the section to speak in terms of reproof [that they were sacrificing to the host of heaven] and to say to them now that they were not observing the commandments of G-d, every man doing what was right in his own eyes. [On the contrary, Verses 4-15 contain a positive discussion of the chosen place that awaited them in the Land of Israel.] And how could Moses our teacher say “We are committing sins!” Forbid it! Instead he should have said “You shall not do after all that ‘you’ have done to this day, every man whatsoever is right in his own eyes.” And what sense was there to include among the sins the commandments that depend on the Land?
Rather, the meaning of the verse is as follows: “When the Israelites were in the wilderness they were commanded to slaughter all their cattle and sheep as peace-offerings before the Tabernacle, but they would perform [the Service of the offerings] in whatever place the Tabernacle was [that is, wherever it halted rather than in a fixed location]. And if someone …

איש כל הישר בעיניו, in every location in the desert where we put up the Tabernacle after making camp we offer our sacrifices.