John Calvin Commentary Deuteronomy 31:28

"Assemble unto me all the elders of your tribes, and your officers, that I may speak these words in their ears, and call heaven and earth to witness against them." — Deuteronomy 31:28 (ASV)

Gather to me all the elders of your tribes. Special reference is made here to the Song, which, we gather from the last verse, was recited alone. Indeed, Moses appears to contradict himself when he commands only the elders and officers to be called to listen, while he soon afterward records that he read it to the whole people.

But these two things are easily reconciled when we remember the customary order he observed in gathering the multitude. For it is clear from many passages that they were not called together indiscriminately; instead, the heads of tribes and the princes of the people each led their own group. Thus, the assembling of the elders mentioned here, far from excluding the rest of the multitude, instead indicates that the whole people were gathered together by their tribes and classes.

We may infer this from the context, for surely he did not call heaven and earth to record against only the officers, and yet this is what he seems to signify. Therefore, under the leaders, the whole multitude is included.