John Gill Commentary Numbers 27:13

"And when thou hast seen it, thou also shalt be gathered unto thy people, as Aaron thy brother was gathered;" — Numbers 27:13 (ASV)

And when you have seen it
Which was all he was admitted to; for to go into it and see it was not allowed him, though he importuned it, (Deuteronomy 3:25Deuteronomy 3:26) ,

you shall be gathered unto your people ,
as Aaron your brother was gathered; die as he did, in the same sudden, easy, quiet, and cheerful manner; see (Numbers 20:26–28) .