John Gill Commentary Genesis 45:17

"And Pharaoh said unto Joseph, Say unto thy brethren, This do ye: lade your beasts, and go, get you unto the land of Canaan;" — Genesis 45:17 (ASV)

And Pharaoh said to Joseph
Who, it is highly probable, waited upon Pharaoh to acquaint him with the coming of his brethren; for it cannot be imagined that Pharaoh should say what follows upon a bare report, without having a further account of things from Joseph, or that he would neglect giving it, but take the first opportunity to inform him, whereupon he gave him the following order:

say to your brethren, this do you ;
give them directions and instructions to do as follows:

load your asses :
with provisions for the present necessity of their father's household in Canaan, and for their journey back to Egypt:

and go, get you into the land of Canaan ;
with all the haste they could make.