The Wisdom of Israel, by Edwin Collins, , at sacred-texts.com
When God revealed himself to Moses at the burning bush, He broke off between calling to him and revealing His will; but at the revelation in the Tabernacle in the wilderness, there was no break; while in the former case Moses was held, as it were, at a distance, and not in the latter.
This may be compared to a king of flesh and blood, who is angry with one of his servants and orders him to be imprisoned. When he commands the messenger that is to announce the punishment, he does so only outside his royal dwelling, and keeps the messenger at a distance and deliberates before issuing the decree. Thus when God revealed Himself to Moses at the burning bush, it was to announce punishments to Pharaoh, who also was one of God's creatures and therefore loved by Him.
The revelation in the Tabernacle, on the contrary, was a message of mercy and love only, made when God was rejoicing in His children, and when the children of His house were rejoicing in Him. Then He spoke commands to His messenger from within, as a father would speak to one of his children and place him on his lap and place a hand upon his head.