Now it fell on a day, that Jonathan the son of Saul said to the young man who bore his armor, Come, and let us go over to the Philistines' garrison, that is on yonder side. But he didn't tell his father.
Half a furrow of land (1 Samuel 14:14) was half a parcel of land that a yolk of oxen could plow in one day. Evidently God assisted Jonathan by sending a mild earthquake to unnerve the Philistines further (1 Samuel 14:15; cf. Deuteronomy 7:23).