The sedrah begins almost a year after the Exodus from Egypt, on Rosh Chodesh Nisan. After seven days of inaugurating the Mishkan (Tabernacle), Moshe instructed Aharon to bring two special offerings, an elevation offering (olah) and a sin offering (chatat). The people were also told to bring a chatat, two olah offerings and two peace offerings (shelamim). Aharon approached the altar (mizbeach), together with his sons, and they began the process of bringing these offerings.
Aharon and his sons finished the offerings, after which Aharon blessed the people with the priestly blessing. Moshe and Aharon then blessed the people that the Divine presence will rest upon them.
A fire came from heaven and consumed the offerings on the mizbeach. The people fell to the ground in awe of God. Nadav and Avihu, two of Aharon’s sons, brought an incense offering (ketoret) in a pan, which they had not been commanded to do. A fire descended from God, killing them instantly. Aharon was silent. Moshe asked two of their cousins to remove the bodies. Moshe told Aharon and his two surviving sons, Elazar and Itamar, not to display any mourning in public. God said to Aharon that no one is allowed to perform the service in the Mishkan when drunk.
Moshe told Aharon and his sons to eat the remaining parts of a special meal offering (mincha) that they themselves had brought that day, as well as parts of the shelamim offering which they had also brought.
Moshe criticised Elazar and Itamar (Aharon’s other sons) for burning one of the chatat offerings instead of eating parts of it. Aharon defended their actions, based on their status as mourners. Moshe accepted Aharon’s justification.
God taught Moshe and Aharon some of the laws of kashrut. Only an animal with completely split hooves and which chews the cud is kosher. Therefore, animals like the camel and pig, which have only one of these characteristics, are forbidden. Fish are only kosher if they have both fins and scales. The Torah lists forbidden birds by name. Flying insects are also prohibited food, with limited exceptions (that are today difficult to identify). Kosher animals that die without proper slaughter (shechitah), as well as dead non-kosher animals, transmit ritual impurity (tumah) to one who touches them.
The Torah lists some basic laws of how certain utensils can become impure (tameh) and how they need to be treated thereafter. All creeping insects are forbidden to eat. Keeping these laws allows a person to become sanctified and holy.