And if they blow [but] with one [trumpet]
With only one of them, or but once, with one sounding, and that an even one as before:
then the princes, [which are] the heads of the thousands of Israel,
shall gather themselves unto thee:
and they only or alone, as Aben Ezra: by this token, or by this difference of blowing both trumpets, or only one, it was, easily known when the whole congregation or when the princes only were to meet Moses at the same place, the door of the tabernacle of the congregation; and all are to attend divine service, and the ministry of the word, even the whole church of God, and all the members of it, high and low, rich and poor, princes and people.