John Gill Commentary Numbers 16:50

"And Aaron returned unto Moses unto the door of the tent of meeting: and the plague was stayed." — Numbers 16:50 (ASV)

And Aaron returned unto Moses
After he had by his atonement and intercession put a stop to the wrath of God broken forth upon the people:

unto the door of the tabernacle of the congregation ;
where Moses was waiting for his return, and to know the issue of this affair:

and the plague was stayed :
even before Aaron left the camp, and is here repeated for the certainty of it, and to intimate that it continued to cease, and broke not out again.