Boyd’s Bible Dictionary:
Like the trespass-offering, the sin-offering was expiatory
It was presented on the great day of atonement, when one confessed the sins of the nation with his hand on the head of the scapegoat (Lev. 16:1-34; Num. 18:9).
Concise Bible Dictionary:
See OFFERINGS.
From Manners and Customs of the Bible:
Leviticus 6:25. This is the law of the sin offering.
There were two kinds of sin offering: one for the whole congregation and the other for individuals. For the first kind a young bullock was brought into the outer court of the Tabernacle, where the elders laid their hands upon his head and he was killed. The high priest then took the blood into the Holy Place and sprinkled it seven times before the wail, putting some on the horns of the golden altar of incense. The remainder of the blood was then poured out at the foot of the altar of burnt offering. The fat of the animal was burnt upon the altar, and the rest of the body was taken without the camp and burnt (Lev. 4:13-21).
Of the second kind of sin offering there were three varieties. The first was for the high priest. The ceremonies only slightly varied from those just described (Lev. 4:3-12). The second was for any of the rulers of the people. A kid was killed instead of a bullock. The priest did not enter the Holy Place, but merely put some of the blood on the horns of the altar of burnt offering, and poured the rest out by the foot of the altar. The fat was burned upon the altar (Lev. 4:22-26). The third was for any of the common people. A female kid or lamb was brought and treated as in the case just described (Lev. 4:27-35). If poverty prevented the procuring of kid or lamb, two turtle doves or two young pigeons could be substituted; and for the very poorest a small offering of fine flour (Lev. 5:7-13).
What was left of the sin offering for one of the rulers or for one of the common people was not burned without the camp, as in the two other instances, but was eaten by the priests and their sons. It was considered peculiarly holy, and special directions were given concerning the vessels in which it was cooked (Lev. 6:24-30). The sin offering was offered for sins of ignorance against negative precepts (Lev. 4:2,13,22,27).
Related Books and Articles:
Ministry Nuggets:
• In the sweet savor offerings, when the worshiper laid his hand upon the head of the offering, it signified that all the acceptability of the sacrifice was his; he was identified with all the sweet savor of the sacrifice. But in the sin offering it was just the other way. Instead of the offerer being identified with the sweet savor of the sacrifice, the animal- the offering-was identified with the man's sin; his sin was transferred to the head of the animal. (“Christ as Seen in the Offerings: Sin and Trespass Offerings” by R.F. Kingscote)
• I suppose these sin offerings were not really to bring the people into relationship with God, but to restore to communion those who already were in relationship with Him. And therefore, if the high priest sinned, or the congregation sinned, the communion of the whole of the people was interrupted, because the high priest represented the people. Accordingly, the blood of the sin offering for the high priest, or for the congregation, was taken inside the tabernacle, and sprinkled before the veil. (“Christ as Seen in the Offerings: Sin and Trespass Offerings” by R.F. Kingscote)
• As the high priest represented the people, so his acts brought, not only blessing on them, but also the guilt of his sin. How blessedly in contrast is the High Priest of our confession, a great High priest, passed through the heavens as He is, Jesus the Son of God! (“Chapter 14. Sin Offering for the Priest: Leviticus 4:1-12” by W. Kelly)
• Blood is brought not only "to" but "into" the tent of meeting, and sprinkled before the veil of the sanctuary. Only on the solemn and single day of atonement did the high priest go with incense within the holiest and sprinkle of the blood upon the mercy-seat and before it. (“Chapter 14. Sin Offering for the Priest: Leviticus 4:1-12” by W. Kelly)