Parashas Naso · Passuk 7:10
The chieftains also brought the dedication offering for the altar upon its being anointed. As the chieftains were presenting their offerings before the altar,
Chabad.org — English translation + Rashi
Source: Bamidbar Rabbah 13:2.
English: “Before the altar” — what is “before the altar”? Because they came and stood before the altar, and Moshe did not accept [the offerings] from them until it was said to him from the mouth of the Holy One.
In context: Moshe hesitated to accept the princes’ gifts until explicit divine authorization was given.
Custom
Chazal teach that Moshe waited for divine permission before accepting the offerings of the nesi’im.