Leviticus gives the sin offering for cases where someone sins unintentionally against the LORD’s commandments. The required animal varies by the person’s role (anointed priest, whole congregation, ruler, or common person), and the priest applies blood in specified ways. The chapter repeats that “the priest shall make atonement… and he shall be forgiven” (Leviticus 4:2–3; Leviticus 4:20).
These opening lines introduce a new set of instructions in Leviticus: Yahweh communicates to Moses, and Moses must pass the message on to Israel. The situation in view is when a person breaks one of Yahweh’s prohibitions without realizing it at the time. Leviticus 4 begins with the standard speech-formula that marks a fresh block of instruction, linking divine speech to Moses and then to the people. It follows the earlier material about offerings in Leviticus 1–3, and it opens the section that will lay out procedures for dealing with this particular kind of offense.
Leviticus 4:1–2 introduces a new instruction block: Yahweh speaks, Moses relays, and Israel is addressed. The passage frames what follows as divine direction rather than Moses’ personal policy (explicit in the speech formula). The stated situation is a person who “sins unwittingly” by doing something Yahweh has commanded not to be done.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Leviticus 4:2-3, then read the surrounding section so the answer stays connected to the passage's flow.
2Speak to the children of Israel, saying, If anyone shall sin unwittingly, in any of the things which Yahweh has commanded not to be done, and shall do any one of them:
3if the anointed priest shall sin so as to bring guilt on the people, then let him offer for his sin, which he has sinned, a young bull without blemish to Yahweh for a sin-offering.