A few remarks on the way the sacred writers make use of the verb כִּפֵּר may not be without interest.
It is used without, or with prepositions. Without, where the thing to be covered is the prominent thought, e.g., sin (Dan. 9:24; Psa. 65:3 (4); 78: 38); the land, and the people of Israel (Deut. 32:43); the altar (Ezek. 43:20).
We meet with the verb followed by; in Lev. 6:30 (23); 16: 17, which tell of the place; in Lev. 7:7; 1 Sam. 3:14; 2 Sam. 21:3; Num. 5:8, which speak of the means by which atonement could be effected. Where the one by whom it is made is the prominent thought, we meet with the verb in connection with בְּעַר to tell us on whose behalf he is acting-e.g., Lev. 9:7; 16: 6, 11, 17, 24; Ex. 32:30; Ezek. 45:17; and in 2 Chron. 30:18, where Hezekiah looks to the Lord to effect it.
Where things inanimate involved in man's guilt, but guiltless themselves, are spoken of, the verb can be followed by אֶח (Lev. 16:20,33; Ezek. 43:26; 45: 20); and where persons are before the writer's mind, whether guiltless themselves of the actual transgressions or not, we meet with the preposition לְ
e.g., Deut. 21:8; Isa. 22:14; Ezek. 16:63.
But when the guilt, and the dealing with it, is the uppermost thought, we have used, pointing out on whom or on what the sin rested, which was to be covered, whether (1), the sinner's; (2), the place of standing; or (3), the victim to which the sin was transferred-e.g. (1), Lev. 4:20,26,31,35;12: 7; 14: 18-20; 19: 22; Num. 15:25,28; (2), Ex. 30:10; Lev. 16: 16; (3), Lev. 16:10. Keeping in mind what is said to be the primary meaning of the verb, we can understand then its use in the different places referred to; and the force of Heb. 10:4, Rom. 3:25, is felt. The sins of God's people in old days were covered by the blood, and so God passed by them.
At times we meet with the fuller forms of expression (a) מִ٠ז על בִּפֵּר, and (b),כִּפֵּר (a), Lev, 5: 6; 14: 19; 15: 30; 16: 16, 34; (b), Lev. 5:16; Num. 5:8; the former marking from what, and the latter by what, the sin was covered; but always, where the sin is the prominent thought, we meet with עַל of the person or thing in whom it is covered. See Lev. 16:33, where we have אֶח כִּפֶּר of the sanctuary and vessels, and עַל כַּפַּר of the people.