John Gill Commentary Exodus 34:5

"And Jehovah descended in the cloud, and stood with him there, and proclaimed the name of Jehovah." — Exodus 34:5 (ASV)

And the Lord descended in the cloud
The same with the cloudy pillar, which was now gone up from the door of the tabernacle, and was on high in the air over the mount, and on which the Lord now descended in it, as he had before, (Exodus 19:9Exodus 19:16Exodus 19:18) :

and stood with him there ;
not Moses stood with the Lord, as the Vulgate Latin version; but the Lord, or the cloud in which the Lord was, stood near to Moses:

and proclaimed the name of the Lord :
Jehovah declared with a loud voice out of the cloud, that the Lord was there; the Targum of Jonathan is,

``and Moses called on or in the name of the Word of the Lord;'' and so the Vulgate Latin version refers it to Moses, and renders the words, "calling on the name of the Lord"; but the following verse clearly shows that it must be understood of the Lord, and not of Moses.