Saul was afraid of David, because the Lord was with David but had departed from Saul.
NMVAnd Sha’ul [desired] was afraid of David [beloved], because the LORD-Yehōvah (Messiah Pre-Incarnate) was with him, and was departed from Sha’ul [desired].
OJBAnd Sha'ul was afraid of Dovid, because Hashem was with him, and was departed from Sha'ul.
T4TBecause it became evident that Yahweh had abandoned Saul but that he was helping David, Saul was afraid of David.