NOTES for Exo 10:1-29
A moment comes when even Pharaoh understands: something must be done, or his country will not survive the disasters falling on it one after another. This moment was very unpleasant for him: he had to agree to something he did not want to agree to at all. There were all kinds of considerations, including purely political ones: letting a large mass of people go somewhere into the wilderness, where all those people would remain without supervision or control, was risky.
Pharaoh tries to find a way out: he wants to agree with Moses in advance on how many people will go with him and exactly who they will be. Moses, by contrast, gives Pharaoh no details. He asks that everyone be allowed to go, and with the livestock as well, since no one knows which animal from the herd God will choose for Himself as a sacrifice. This answer made Pharaoh wary: he immediately assumed that Moses was plotting something bad.
Here, as in a drop of water, we see reflected that universal problem, the problem of original mutual distrust, which poisons the life of fallen humanity. When we look at others, evaluate their plans, and peer into their intentions, we are always inclined to assume the worst. Moses really did intend in the end to lead his people out of Egypt; that is true. But he was hardly lying to Pharaoh about his intentions at the moment when he spoke of them.
Judging by how events developed later, one may think that the decision to leave Egypt and not return was made by Moses only when it became clear that Pharaoh would not accept the people in their new spiritual condition, the condition they would acquire after entering into a union-covenant with God. If it had been otherwise, it is possible that even after the covenant at Sinai the Hebrews would not have left the country immediately. After all, by leaving as unexpectedly as they did, the fugitives proved completely unprepared either for life in the wilderness or for the path after God.
Preparation required time, which under other circumstances and with a different attitude from the authorities toward what was happening could well have been spent in Egypt. Pharaoh's position, however, made that course of events completely impossible. When Pharaoh directly forbade Moses to appear before him again and to return to the question Moses had set before him, the prophet understood: the time for requests was over; now everything would go differently, according to another scenario.