... Exodus Rabbah 1:27 (commenting on Exodus 2:11 and the end of the first Egyptian phase of his life) says, “Moses was twenty years old at the time; some say forty” (see also 1:30 on Exodus 2:14). Stephen in Acts 7:23 puts his age at forty when he “visited his relatives” and soon after had to flee the country and in 7:30 credits forty years to his sojourn in Midian, so that his 120 years consisted of three forty-year periods (see verse 36 for the forty wilderness years). The same division is attested in Genesis Rabbah 100:10: “Moses spent forty years in Pharaoh’s palace, forty years in Midian, and served Israel forty years.” The writer of Jubilees comes very close to the system of three forty-year units but modifies it slightly so that the first period consists of twenty-one plus twenty-one years, perhaps because of his fondness for sevens but especially from the need to give him a proper Israelite upbringing. This will leave only thirty-eight years for his time in Midian (see 48:1 and the commentary there). ...