Nobody can tell exactly when Jacob realized that God had met all his conditions (28:20,21).
The last condition was about to be fulfilled: returning safely to his father’s household. Now Jacob became afraid and he wrestled with God. Only when we have wrestled with God ourselves, we know that the unbelievable is true: God - the Almighty - is willing to lose if we insist on winning at all costs, and Jacob experienced this too in his wrestle with God.
God did not demand submission from Jacob, even though He - the Eternal One - had met all the conditions of mere little Jacob… And when God was about to leave, Jacob was not pleased at all that he had almost won. This victory would have meant his greatest defeat.
God might have struck him down, but God takes no pleasure in a sinner’s death (Ezekiel 18:32). He stroke Jacob in such a way that he was crippled for the rest of his life. But Jacob did not let go of God. For in his struggle with God, Jacob had come to know Him as the One he could not live without any more. And then we read that wonderful word from a man who did not dare to surrender, ‘I will not let You go unless You bless me’ (:26)!
Is this not the outcry of any man, inwardly resisting what is actually his heart’s desire: to submit himself wholly to God?! God knows how all of us, from a deep-seated fear of life, try to vindicate ourselves, even before Him.
But God does not avoid wrestling with us, until we dare to submit ourselves to His great Love.