Leviticus 14:21
And if he be poor, and cannot get so much; then he shall take one lamb for a trespass offering to be waved, to make an atonement for him, and one tenth deal of fine flour mingled with oil for a meat offering, and a log of oil;
Cross-references
Leviticus 14:10 describes the full offering for the wealthy, while this verse provides a reduced alternative for the poor.
Leviticus 14:32 summarizes the law for the poor person's cleansing, directly tying back to the reduced offering here.
In Leviticus 5:7, the same sliding scale allows the poor to bring birds instead of a lamb for a guilt offering — identical compassionate provision.
In Leviticus 12:8, the same substitution of birds for a lamb is allowed for a poor woman after childbirth — a parallel poverty provision.
Leviticus 27:8 applies the same sliding-scale principle for vows, allowing the poor to pay less according to their ability.
2 Corinthians 8:12 teaches that giving is acceptable according to what one has — exactly the same principle of proportionate offering seen here.
Luke 5:14 directly references this law, instructing the healed leper to offer what Moses commanded for cleansing.