Mishnah for Sotah 8:3

One who vowed [that his friend could not benefit from him] unless he eats with him, and the friend does not trust him in respect of tithes, he may eat with him on the first Shabbat even though he does not trust him in respect of tithes, provided that his friend said to him that the food had been tithed. But on the second week, even though he had vowed that he would not benefit from him, he may not eat with him unless he first tithed [the produce].

One who vowed [that his friend could not benefit from him] unless he eats with him, and the friend does not trust him in respect of tithes, he may eat with him on the first Shabbat even though he does not trust him in respect of tithes, provided that his friend said to him that the food had been tithed. But on the second week, even though he had vowed that he would not benefit from him, he may not eat with him unless he first tithed [the produce].

A sheaf left near a stone fence, or near a stack [of grain] or near oxen, or near equipment: Bet Shammai says: it is not considered “forgotten”; Bet Hillel says: it is considered “forgotten.”