Nehemiah 12:9

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

Cross-reference

Nehemiah 12:24 describes Levites standing opposite to praise and give thanks—mirroring the 'stood opposite them' service here.

Nehemiah 11:17 names Bakbukiah as second among Mattaniah's brothers—the same person standing opposite in service here.