וַֽיהוָ֞ה הֶאֱמִֽירְךָ֣ הַיּ֗וֹם לִהְי֥וֹת לוֹ֙ לְעַ֣ם סְגֻלָּ֔ה כַּאֲשֶׁ֖ר דִּבֶּר־לָ֑ךְ וְלִשְׁמֹ֖ר כָּל־מִצְוֺתָֽיו׃
et l’Éternel t’a glorifié à son tour en te conviant à être son peuple privilégié, comme il te l’a annoncé, et à garder tous ses commandements.
Or HaChaim
There is another element to the meaning of the word לאמור here, similar to the meaning of Deut. 26,18: וה׳ האמירך, i.e. that there was a mutual bond being created between the Israelites and G'd by their acceptance of the Ten Commandments.
Or HaChaim
Alternatively, G'd demonstrated how much He valued Moses by showing that even when His message concerned primarily Aaron He did not address Aaron with that message but Moses. We may understand the very words ויאמר ה׳ אל משה in a way similar to Deut. 26,18: וה׳ האמירך היום, "and G'd achieved by speaking to you this day, etc." Bamidbar Rabbah 14,21 comments on this that even where we find the Torah reporting that G'd "spoke to Moses and Aaron," the meaning is that Moses was to tell Aaron what G'd had said to him. Our verse then is proof of that statement seeing that G'd addressed Moses even when the commandment He wanted to communicate was addressed exclusively to Aaron.
Ibn Ezra
אמיר The top of the olive-tree.8A. V., The uppermost bough. Comp. האמירך He hath exalted thee (Deut. 26:18); the word אמיר has the same meaning in Arabic.9أَمِير chief. Comp. Sephath Yether 47.