From The Openness of God:
Philo is well aware of the many texts that say that God repents (changes his mind) or feels anger. In Philo’s mind such texts are not to be taken literally; rather, they are anthropomorphisms for the benefit of the “duller folk” who cannot understand the true nature of God. “For what greater impiety could there be than to suppose that the Unchanging changes?” Philo leans on Numbers 23:19, which in the Septuagint reads: “God is not as man.”39 Because God is not like us, he cannot change his mind. Moreover, since God foreknows all that will happen, divine repentance is impossible. Consequently, though Philo struggled against a static conception of immutability, in the end, the Greek metaphysical understanding of divinity ruled his interpretation of the biblical texts that describe God as genuinely responsive.