Or HaChaim on Numbers 7:10/אור החיים על במדבר ז׳:י׳

1 ויקריבו הנשאים את חנוכת המזבח, The princes brought the dedication-offering for the altar. It appears that all the princes wanted to offer their gifts on the first day on which the altar was being inaugurated, as they all wanted to be part of this inauguration together. G'd, however, said that only one prince per day could offer his respective offering. This is why the Torah added that the period of inauguration extended for the entire twelve days during which the princes offered their gifts (compare wording in verse 11 where the word לחנוכת המזבח appears once more). In this instance G'd did not have to tell Moses "accept it from them!." This means that Moses did not need to obtain G'd's permission to accept these gifts. He had no doubt about G'd's willingness to accept the princes' offerings including the gold and the silver vessels. The only reason that G'd had to involve Himself was that all the princes wanted to bring all their gifts on the same day. I have seen the following comment by Sifri on our verse: "The verse reveals that just as the princes had made free-willed contributions to the materials from which the Tabernacle was constructed so they now contributed for the inauguration of the altar; Moses did not want to accept this from them until he had been instructed to do so by G'd Himself, and that is why the Torah wrote: 'they shall offer their offerings for the inauguration of the altar.'" The author of the Sifri derived this from the apparently superfluous words יקריבו את קרבנם, which he interpreted as permission for Moses to accept the offerings. We must examine why Moses refused to accept these offerings until G'd had given permission for them to be accepted. Perhaps Moses was not sure whether the inauguration of the altar was the province of Aaron and himself or that of the princes. This was especially so seeing the list of princes did not include a representative of the tribe of Levi. Please read what we have written in this connection at the beginning of Parshat Beha-alotcha.

2ויקריבו הנשאים, the princes offered, etc. The reason the Torah repeats this expression once more is to tell us that the princes went to the trouble to bring the entire gift up to the entrance of the Tabernacle personally, although this might have been considered below their dignity seeing they were "princes." Another reason why the Torah repeated this expression is that instead of handing their sacrifice over to the priest who was to present (part of) it on the altar, they themselves placed it at the entrance of the Tabernacle close to the altar. They hinted by their action that they wished their respective offerings to be the first to be presented on the altar on that day. When the Torah writes in a similar vein in verse 3 that the princes brought the wagons to the Tabernacle, this also means that they wished their gifts to be the first ones to be accepted by the Temple -treasury on that day.