Exodus 12:1

ויאמר ה' אל משה ואל אהרן AND THE LORD SPAKE UNTO MOSES AND AARON — Because Aaron had worked and toiled in performing the wonders just the same as Moses He paid him this honour at the first command by including him with Moses in the communication (Tanchuma Yahshan 2:3:8). בארץ מצרים IN THE LAND OF EGYPT — This must have been outside the city! Or perhaps this is not so, but it was inside the city? Scripture however states, (Exodus 9:29) “When I leave the city [I will spread my hands (pray) unto the Lord]”. Now how was it in regard to prayer which is of light importance in comparison with a communication from God? He did not recite the prayer inside the city! Then, in the case of a divine communication which is of so weighty importance does it not follow all the more that this was also so! — And why, indeed, did He not converse with him inside the city? Because it was full of idols (Mekhilta).

And the Lord spoke to Moshe and Aharon in the land of Miżrayim, saying,

וַיֹּ֤אמֶר יְהֹוָה֙ אֶל־מֹשֶׁ֣ה וְאֶֽל־אַהֲרֹ֔ן בְּאֶ֥רֶץ מִצְרַ֖יִם לֵאמֹֽר׃