1. Numbers 3:1 (ESV)
  2. Exposition

Why is Aaron mentioned here before Moses?

Numbers 3:1 (ESV)

1 These are the generations of Aaron and Moses at the time when the LORD spoke with Moses on Mount Sinai.

Aaron is mentioned before Moses, because the focus is now shifting toward Aaron and his sons, since they had been anointed as priests (see Leviticus 8:1 – 9:24).