John Calvin Reformed @genevareformer

18. And he went out. We have stated why the holy Prophet went out from the king to pray, viz., because he was not worthy that the sacred name of God should be invoked in his presence. Therefore Moses did not offer prayer for him, because he thought him to be really converted, but that he might open God’s way for the remaining contests.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The invasion of the land by the locusts - God's great army, Joe 2:11. God bids Moses stretch out his hand (Exo 10:12), to beckon them, as it wee (for they came at a call), and he stretched forth his rod, Exo 10:13. Compare Exo 9:22 23.

Commenting on Exodus 10:12-20

John Gill Reformed Baptist @doctorgill

And he went out from Pharaoh,.... Without the city, as he had been wont to do: and entreated the Lord; prayed to him that he would remove the plague of the locusts from the land. And he went out from Pharaoh,.... Without the city, as he had been wont to do: and entreated the Lord; prayed to him that he would remove the plague of the locusts from the land.