The chambers - Render it: and chambers, not yet described. They were north of the altar, by the “posts” or pillars in front and along the sides of the gate-building. There were several gates in the gate-building.
SDA Bible Commentary (limited)
Volume 1-7
38. Where they washed. The proximity of the present passage to the description of the north gate (vs.35-37) has led some to the conclusion that the furnishings here described belonged to that gate. Others believe a new section is here introduced and that the east gate is under consideration (see vs.40, 44; chs.43:17; 46:1, 2).