Samuel I, 16: on seers and shepherds

“Ruddy/Redheaded” Rabbi Abba bar Kahana said: As though he were a shedder of blood. When Samuel saw that David was ruddy, as it is written: “He sent and brought him and he was ruddy” (I Samuel 16:12), he was afraid and said: ‘This is a shedder of blood like Esau.’ The Holy One blessed be He said to him: “With beautiful eyes” (I Samuel 16:12). Esau killed at his own initiative, but this one kills at the initiative of Sanhedrin.

He mentioned that they sent after David, who was the youngest and was herding the sheep. And this is a sign that he will herd his people like the flock of Joseph. It is written in Midrash Tanhuma: "The Lord examines the righteous (Psalm 11:5), and how does He examine him? Rabbi Isaac said: through herding. David was tested through herding, as it is written: "he is keeping the sheep". Amos was similarly tested, as it is written "I was neither a prophet nor the son of a prophet, but I was a shepherd" (Amos 7:14). Moses was tested through herding, as it is written: "Now Moses was tending the flock of Jethro his father-in-law" (Exodus 3:1). Jacob was tested with sheep, as it is written: "In breeding season I once had a dream" (Genesis 31:10).

For an instrument is a gathering of the ruach, which is a mixture of good and evil. There is a ruach of depression, a gloomy ruach, a ruach of evil, as it is said of Shaul, “an evil ruach began to terrify him” (1 Samuel 16:14). There is also a good ruach, as it is written, “Let Your good ruach guide me on level ground” (Psalms 143:10). This is the aspect of the ruach of prophecy, Divine ruach.

Skilled in music; he is a stalwart fellow and a warrior, sensible in speech, and handsome in appearance, and the LORD is with him.” "Skilled in music" in the bible, "a stalwart fellow," in Mishnah, "a warrior" in Talmud, "sensible in speech" in good deeds, "handsome in appearance," since he would make faces shine in Halachah, "the Lord is with him" and Halachah follows his opinion.