The Gemara says that learning without song is called: ח וּקִים לֹא טוֹבִים “laws that are no good”. Dovid wanted his Tehilim to be as Chashuv as Nega’im and Ohalos (the deepest topics of Torah) (Medrash), and he once said: זְמִרוֹת הָּיוּ לִי חֻקֶיךָ תהלים קיט נד Your commandments are to me like a song. The Gemara says that that Dovid HaMelech learned Torah the first half of the night, and the other half he sang praises to Hashem. R’ Zundel of Salant Zatzal explains that he sang in appreciation and Simcha over the Torah that he had just learned.
Perhaps this is why he was so against Doeg HaEdomi, despite his being a major Talmid Chochom (the Passuk calls him: אַבִיר הָּרוֹעִים אֲשֶר לְשָּאוּל ש"א כא ח the strongest Sheppard of Shaul, i.e., he was the Av Bais Din. Medrash). First, he cursed him, and Doeg was Niftar in his 30s. (Gemara). And when Hashem wanted to give Doeg Olam HaBah because Hashem loved his Torah; Dovid objected. Even allowing his Divrei Torah to be repeated after his Petira (so he would have the Zechus of: שִׂ פְתוֹתָּיו דוֹבְבוֹת בַקֶבֶר having his lips move in his grave), Dovid objected to, and Hashem “gave in” to him. (Gemara).
