This seems to have been a second vision, whereby God calls him forth to the present and speedy execution of that command which before was more generally delivered. Which sought thy life, to wit, to take it away. See the like expression, 1 Samuel 22:23 1 Kings 19:14 Matthew 2:20. God knew very well that one great cause of Moses's unwillingness to this undertaking was his carnal fear, though he was ashamed to profess it, and therefore gives him this cordial.
Related Commentaries of Exodus 4:19
Exodus 4:19
19 And the LORD said unto Moses in Midian, Go, return into Egypt: for all the men are dead which sought thy life.