Once in a year, on the day of expiation, Leviticus 16:19 Numbers 29:7. With the blood of the sin-offering of atonements; to note, that the prayers of the saints are acceptable to God no otherwise but through the blood of Christ, who was offered for the expiation of our sins.
Related Commentaries of Exodus 30:10
Exodus 30:10
10 And Aaron shall make an atonement upon the horns of it once in a year with the blood of the sin offering of atonements: once in the year shall he make atonement upon it throughout your generations: it is most holy unto the LORD.