‘He also measured the vestibule of the gate towards the house which was one reed. So he measured the vestibule of the gate, eight cubits, and its posts, two cubits, and the vestibule of the gate was towards the house. And the side rooms of the gate eastward were three on this side and three on that side, the three were of the same size, and the posts were of the same size on this side and on that side. And he measured the breadth of the opening of the gateway, ten cubits, and the breadth of the gate, thirteen cubits.'
‘Towards the house' indicated that this vestibule was at that end of the gateway nearer the sanctuary, rather than at the outer end. So the inner protecting gate was also measured by God's representative. The six guard rooms are again described, emphasising their importance in relation to the protecting gate. The way to God had to be fully protected from profanity. There was a way in but it had to be guarded and kept for those for whom it was allowed. The measuring of them stresses that they were there and that they had to be taken into account.
The eight cubit vestibule plus the two one cubit posts, presumably make up the ten cubit opening of the gateway. Emphasis again is on multiples of five.