Mishnayos Kilayim Perek 4 Mishnah 2

מחול הכרם – it is a free space between the vineyard to the fence all around, like (see Judges 21:21: “[As soon as you see the girls of Shiloh] join in the dances, come out from the vineyards; [let each of you seize a wife from among the girls of Shiloh, and be off for the land of Benjamin]) women joining in the dancing that they dance all around. It is the language of (Jeremiah 31:13): “Then shall maidens dance gaily.”

אם יש שם י"ב אמה – according to the words of the School of Hillel, they provide four cubits for the tilling of the vineyard and sow the remainder. But if there aren’t there twelve cubits, he should not bring seed to there, for the four cubits that are near the wall, since they are not sown because of the repair of the wall in order that a person can walk upon the ground near the wall, and that the dirt will be threshed and its foundations will be strengthened, they are declared free. But the middle sections, if there are four cubits they are considered [usable] but if not, they are nullified in regards to the vineyard, but here we don’t require sixteen cubits for there is no prohibition other than from one side. And all of these cubits are a cubit of six handbreadths.