Numbers 3:16

על פי ה׳ [AND MOSES NUMBERED THEM] ACCORDING TO THE WORD OF THE LORD — Moses said to the Holy One, blessed be He, “How can I enter their tents to ascertain the number of their babes?!” Thereupon the Holy One, blessed be He, replied to him, “You do your share and I will do Mine!’ Moses accordingly went and stationed himself at the entrance of each tent, the Shechinah having gone there beforehand, and a divine voice issued from the tent, saying, “So-and-so many babes are in this tent”. It is on this account that it states, “[and Moses numbered them] according to the word (by the mouth) of the Lord” (Numbers Rabbah 3 9).

And Moshe numbered them according to the word of the Lord, as he was commanded.

וַיִּפְקֹ֥ד אֹתָ֛ם מֹשֶׁ֖ה עַל־פִּ֣י יְהֹוָ֑ה כַּאֲשֶׁ֖ר צֻוָּֽה׃