In Act 7:23, Act 7:30, Act 7:36, the life of Moses is represented as embracing three periods, of forty years each; the Jewish writers say the same; and though this is not expressly stated in the Old Testament, his age at death, one hundred twenty years (Deu 34:7), agrees with it.
it came into his heart to visit his brethren - his heart yearning with love to them as God’s chosen people, and heaving with the consciousness of a divine vocation to set them free.