“sitting.” The Hebrew is more literally, “staying,” but Saul was not camped out on the outskirts of Gibeah like he was tenting there under a tree, rather he was regularly there acting in his role as king. Thus, the fact that he was regularly there is represented in Hebrew by the word “staying,” but that could be confusing in English, and so “sitting” more accurately represents to the English readers what Saul was doing, especially since it was under a tree (cp. CEB; NAS; NET; NKJ).
“under the pomegranate tree.” Likely mentioned to highlight Saul’s position as king, getting to sit in the shade while others would stand in the sun (cp. Judg. 4:5).
“at the threshing floor.” The traditional translation, “in Migron,” has always presented difficulty because it has never been located and besides, normally a town would not be located on the outskirts of another town. There is evidence that the meaning likely refers to a threshing floor. Threshing floors were usually large and flat, and thus a good place for a king to sit, and sometimes by the gate or outskirts of the city, as we see at Samaria (1 Kings 22:10). The translation “threshing floor” is espoused by David T. Tsumura and others (D. T. Tsumura, The New International Commentary on the Old Testament: The First Book of Samuel). If the threshing floor was large, it would not be unusual to have trees nearby to provide welcome shade since the grain harvest was always in the hot summer, and the trees could even be close enough to be encroaching upon the threshing floor itself.
“and the people who were with him.” That is, his soldiers.