Chasidut על ברכות 7:23

This is as the Talmud says, as we have already mentioned (Berachot 4), that Yaakov was afraid that his sins changed his relationship with God, and he would no longer be worthy of Divine protection. Yaakov was afraid, even though God had made him a promise. It must be stressed that God’s speech is not like human’s speech. When a word goes forth from man’s mouth, it is gone and he cannot change it. If he wants to say something different, he has to say something different. With God, just as there is no change in His will, as was explained, so too, his words living and enduring. According to man’s actions, so will he see a response in God’s words. That is to say, if he acts properly and walks on the right path, he will see that God’s words are for his amelioration, and vice versa. The Zohar (Vayishlah, 169a) writes that “all of Your words are on condition.” In the source of God’s will there is no change. All of man’s power of choice is based upon the limitations of his perception. And all of his attainment of goodness, wholeness, or bliss, which depends upon his power of choice, is only that which he acquires for himself within the confines of the borders of his awareness and understanding. God’s will even directs those who transgress against His will. Even though they themselves think that they are transgressing His will, God still directs them, in a way that transcends their own perception.