"You shall offer up a cake of the first of your dough as a gift"—Numbers 15:20.
We are commanded to separate a portion of every dough we prepare and give it to the priest.
"And this shall be the priests' due from the people, from those who perform a slaughter, be it an ox or a sheep"—Deuteronomy 18:3.
We are commanded to give to the priest the foreleg, jaw, and belly of any kosher animal that we slaughter.
"The first of the fleece of your sheep [shearing], you shall give him"—Deuteronomy 18:4.
We are commanded to separate the first portion of [a sheep's] shearing and give it to the priest.
This mitzvah applies only in the Land of Israel.