Leviticus 4:9

And the two kidneys, and the fat that is upon them, which is by the flanks, and the caul above the liver, with the kidneys, it shall he take away,

Leviticus 4:9 belongs to the instructions governing the sin offering. When that offering was for a priest or for the whole congregation, its fat — including the two kidneys and the fat upon them by the flanks, and the caul above the liver — was burned on the altar of burnt offering in the court, while the body of the victim was burned outside the camp.

Sin offerings, along with thank offerings, were required in addition to the tenth of all increase due under the tithing system. The required sin offering was proportioned to what had been entrusted, so the larger the capital the more valuable the gift to be returned to God. These offerings were systematic and regular gifts required of everyone rather than of a particular class, belonging to a system marked by the sanctification of property in which God's claims were kept first and Israel was reminded in almost everything to make a return to the Giver.

The verse stands alongside many other required returns and provisions, including tithes, thank offerings, sacrificial offerings, trespass offerings, ransom for the firstborn, firstfruits of flocks and harvest, corners of harvest fields and dropped grain left for the poor and destitute, spontaneous produce of the seventh year for the needy, remission of debts every seventh year, expenses for hospitality and gifts to the poor, and assessments on property, besides special freewill offerings such as those for the tabernacle in the wilderness and the temple at Jerusalem. For the conscientious, these gifts amounted to about one-third of all income for religious interests and for the poor. They were exacted both for the people's own good and to sustain God's service, and faithfulness in them was checked at stated periods by asking whether vows had been performed.