John Gill Commentary Leviticus 9:6

"And Moses said, This is the thing which Jehovah commanded that ye should do: and the glory of Jehovah shall appear unto you." — Leviticus 9:6 (ASV)

This [is] the thing which the Lord commanded that you should
do
Namely, what they had done, bring the creatures and things for sacrifice they had:

and the glory of the Lord shall appear to you ;
either Christ, the brightness of his Father's glory, in an human form, as a presage of his future incarnation, as he frequently did; or some more than ordinary refulgence of glory breaking out of the holy of holies, where God had now taken up his dwelling between the cherubim; or, as Aben Ezra explains it, the fire that should go out from him, and consume the sacrifice, which would be a demonstration of his presence with them, and of his acceptance of the sacrifice.