פּירוש אויף שמואל א 15:27

And he grabbed the corner of his robe. According to the simple meaning, it seems that when Shmuel turned to leave Shaul, Shaul grabbed the corner of Shmuel's [robe], since Shaul was asking him to return until he would prostrate himself in Gilgol, where the Tent of Meeting was. In Midrash Aggadah, however, Amora'im differ; some say that Shaul tore Shmuel's robe, and some say that Shmuel tore Shaul's robe,²⁸As a symbol of his loss of kingship. Another version is that Shmuel tore his own robe as a gesture of dismay. giving over to him this sign, that whoever will tear a corner of his robe, would reign in his place. And that is what Shaul said to Dovid on the day he tore [Shaul's] robe, 'I know that you will surely reign.'²⁹ Below 24:21. See Rashi’s commentary there.