The Gemara uses the Torah's verses to prove which offerings need to be offered specifically in the name of its purpose and for the owner. With a distinction between sin-offerings that are offered in atonement and apology for violating a karet-level sin, as compared to the nazir's sin-offering. Which sacrifices can be learned from other sacrifices, or specifically not? Also, the Korban Pesach, and how its timing is essential, but so too is it essential that it be offered for its specific purpose.