Matthew Poole and continuators on Nehemiah 12:9

9 Also Bakbukiah, and Unni, their brethren were over against them in the watches .

i. e. In the places where they were appointed to stand, and wait, and perform their office, one standing over against another, as it is explained, v. 24. ward over against ward; for the Hebrew word is the same there and here. Others, according to their turns or courses, of which see 1 Chron. 25. 9.