Midrash sobre Shekalim 5:9

...Even though Moshe was the Gizbar: he called others to perform the accounting. The verse does not read ‘these are the records that were drawn up by Moshe’ but instead these are the records that were drawn up at the (LIT mouth) request Moshe. (Moshe did what he could do to be assured that he would be held accountable; accounted for by the mouth of Moshe; the work of the Leviim under the direction of Itamar