Rashi on Numbers 4:12/רש"י על במדבר ד׳:י״ב

1את כל כלי השרת אשר ישרתו בם בקדש [AND THEY SHALL TAKE] ALL THE VESSELS OF MINISTRY, WHEREWITH THEY MINISTER IN THE HOLY PLACE — i.e. in the Tabernacle which is called holy; these were the vessels for the incense with which they performed the ministry at the inner altar.