'Set Apart' in the Bible

Then I set apart twelve of the chiefs of the priests, even Sherebiah, Hashabiah, and ten of their brethren with them,

And the children of the captivity did so. And Ezra the priest, with certain heads of fathers houses , after their fathers houses, and all of them by their names, were set apart; and they sat down in the first day of the tenth month to examine the matter.