וְדָוִ֖ד ה֣וּא הַקָּטָ֑ן וּשְׁלֹשָׁה֙ הַגְּדֹלִ֔ים הָלְכ֖וּ אַחֲרֵ֥י שָׁאֽוּל׃ (ס)
И Давид был самым младшим; и трое старших пошли за Саулом.—
Rashi on I Samuel
Dovid was the youngest. Who had previously been in Shaul's palace to play music before him.