John Gill Commentary Deuteronomy 9:26

"And I prayed unto Jehovah, and said, O Lord Jehovah, destroy not thy people and thine inheritance, that thou hast redeemed through thy greatness, that thou hast brought forth out of Egypt with a mighty hand." — Deuteronomy 9:26 (ASV)

And I prayed therefore unto the Lord
What follows is a different prayer from that in (Exodus 32:31Exodus 32:32) and agrees better with that in (Deuteronomy 9:11Deuteronomy 9:10Deuteronomy 9:13) , delivered before he came down from the mount, yet could not be the same, because delivered at another forty days and nights:

and said, O Lord God, destroy not your people, and your inheritance :
because they were his inheritance, a people whom he had chosen for his peculiar treasure; this is the first argument used, another follows:

which you have redeemed through your greatness ;
redeemed out of the house of bondage, the land of Egypt, by his great power, as next explained:

which you have brought forth out of Egypt with a mighty hand :
inflicting plagues on the Egyptians, particularly destroying their firstborn, which made them the Israelites urge to depart.