What does Exodus 10:17 mean?
After admitting his sin (Exodus 10:16), Pharaoh asks for forgiveness. His comment about being forgiven "only this once" is probably meant as an appeal for sympathy. Though he has rarely admitted being wrong (Exodus 9:27), this expression seems to mean that this is all he dares ask for. He phrases this as a special favor. As with the other plagues (Exodus 8:15, 31–32; 9:34–35), he is insincere. As soon as the danger has faded, he will break his promises and keep the Israelites in slavery (Exodus 10:3–4, 19–20). This is the result of both his own stubbornness (Exodus 5:2; 7:13–14, 22; 8:15, 19, 32; 9:7, 35) and God's divine judgment (Exodus 4:21).Pharaoh does not attempt to speak with God himself. He asks for Moses and Aaron to approach God on his behalf. This makes sense within the Egyptian concept of religion. Most people assumed that only priests or special messengers could speak with a deity. God has always been open to sincere prayers (Psalm 14:2; Galatians 3:28). This was true even when His laws for the nation of Israel included the use of official priests (Leviticus 5:8; 6:6; Numbers 6:10).
It's also to be expected that Pharaoh refers to God as the God of Moses and Aaron. He uses the name spoken earlier by Moses (Exodus 3:15; 10:3) and even by his own servants (Exodus 10:7). This word is Yahweh, usually translated into English as "Lord." Pharaoh had used that name as a snide remark before this plague (Exodus 10:10). Now, he's forced to speak the name of the God of Israel again, but in humility.