John Gill Commentary Deuteronomy 29:15

"but with him that standeth here with us this day before Jehovah our God, and also with him that is not here with us this day" — Deuteronomy 29:15 (ASV)

But with [him] that stands here with us this day before the
Lord our God
Who are before specified according to their dignity, age, sex, and station of life; or rather, "but [as] with him that stands"

and so with [him] that [is] not here with us this day ;
detained at home by illness and indisposition of body, or by one providence or another; so that they could not come out of their tents, and make their appearance before the tabernacle; though Jarchi interprets this of the people of future generations.