John Calvin Commentary Numbers 23:22

"God bringeth them forth out of Egypt; He hath as it were the strength of the wild-ox." — Numbers 23:22 (ASV)

God brought them out of Egypt. He assigns a reason for their constant success; that is, because God has once redeemed this people, He will not forsake the work that He has begun. The argument is drawn from the continued course of God’s blessings; for, since they flow from an inexhaustible fountain, their progress is incessant.

This, however, especially refers to the state of the Church, for He will never cease to be gracious to His children until He has led them to the very end of their course. Therefore, Balaam rightly concludes that because God has once redeemed His people, He will be the perpetual guardian of their welfare. He afterwards teaches that the power with which God defends His people will be invincible, for this is the meaning of the likeness of the unicorn.