Halacha 6: When he sows untithed grain—the prohibited entity has passed, and he is not required to uproot; the crops are considered regular fruits that require separation.
Question 2
Seller claims he sold untithed grain; buyer claims he bought it tithed—what is the law?
Halacha 8: Although generally the burden of proof is on the one who takes from another, the sages penalized the seller who sold untithed grain—and require him to tithe.
Question 3
Why penalize the renter of a field from a gentile to tithe first?
Halacha 12: The sages penalized that the gentile remain without a renter—to compel him to sell the field to Israel, thus preventing land from being lost to Israel.
Question 4
Cohen who bought grain from another Israelite—what to do with tithes?
Halacha 15: The Cohen is penalized for hastening to harvest untithed grain and seizing priestly gifts—therefore they are taken from him and given to other Cohanim and Levites.
Question 5
Cohen sold a field to an Israelite on condition that 'my tithes are forever'—what is the law?
Halacha 19: A condition 'on the condition' like a reservation—is considered as if he reserved for himself the place where the tithes grow, and therefore the condition applies.