The daily grain offering symbolized the high priest’s sinfulness and need for daily forgiveness. Currid (p.83) remarks, Here is the high priest of Israel acknowledging his unholiness before a holy God, and his contrition and need for forgiveness from God.
20 “This is the offering that Aaron and his sons shall offer to the LORD on the day when he is anointed: a tenth of an ephah of fine flour as a regular grain offering, half of it in the morning and half in the evening.