John Gill Commentary Numbers 7:10

"And the princes offered for the dedication of the altar in the day that it was anointed, even the princes offered their oblation before the altar." — Numbers 7:10 (ASV)

And the princes offered for dedicating of the altar
For setting it apart to sacred use and service, even the altar of burnt offering; or rather after it had been sanctified and set apart, when it began to be made use of for sacrifice:

in the day that it was anointed ;
with the anointing oil, whereby it was devoted to sacred service;

even the princes offered their offering before the altar ;
the altar of burnt offering; they brought their vessels for the service of it, and the creatures for sacrifice, and set them before it; signifying what they meant, thereby, that the silver and golden vessels were for the use of it, and the beasts for sacrifice to be offered up on it: and here Jarchi also observes, that Moses would not receive their offering until he knew the mind of God about it, and it was declared to him from himself.