Leviticus 8:12 records the anointing of Aaron with oil, the very event referenced here as 'the day that he anointed them'.

Leviticus 8:30 describes the sprinkling of anointing oil and blood on Aaron and his sons, part of the consecration ceremony mentioned here.

Exodus 40:13 commands the anointing and consecration of Aaron, which is the event referred to here as the day he was anointed.

Exodus 40:15 describes the anointing of Aaron's sons for perpetual priesthood, the same event referenced here for their priestly portion.