Bava Metzia 105 - Disagreements Between a Tenant and a Field Owner

If a tenant-farmer leased a field from his fellow but did not want to weed it and said to the landowner, "What concern is it of yours, since I am committed to giving you your full rental?" - we do not listen to him, for the landowner can reply, "If you lease expired and you don't renew it, the field will grow weeds for me."
If a sharecropper leased a field from his fellow and it did not produce a substantial crop, so that he wants to abandon working the field, if there is enough growing in it to produce a heap, he is obligated to care for it. Rabbi Yehudah says, "What kind of limit is a heap? Rather if there is enough for sowing the field again."