What are "Ne'os Deshe"?
Rashi: Places 1 of grass. This is because he said metaphorically that [he is an animal, and] Hashem is his shepherd. David was in Ya'ar Chares 2 (Shmuel I, 22:5); it was as dry as Cheres (earthenware), and Hashem moistened it from the good of the world to come (Shocher Tov 6). Radak - David said "Kemo Chelev va'Deshen Tisba Nafshi" (63:6). A good shepherd grazes his flock in a place of grass, and pitches his tent there. In the afternoon, he lies them down in the shade of his tent - "Eichah Sir'eh Eichah Tarbitz ba'Tzaharayim" (Shir ha'Shirim 1:7).
Radak: The Aleph is in place of a Vov; it is as if it says Naveh or Navos - "Lekachticha Min ha'Naveh" (Shmuel II, 7:8).
Radak: This is when David fled Sha'ul.
Why does it say "Yarbitzeni"?
Radak (1): Hashem tends Yisrael, and makes them lie down - "Ani Er'eh Tzoni va'Ani Arbitzem" (Yechezkel 34:15).
What are "Mei Menuchos"?
Radak: It flows slowly; it is not a gushing river, lest it inundate them when they come to drink.
Malbim: It is clear water; nothing clouds it.
Why did he say "Yenahaleni"?
Malbim: This discusses when he was brought to Beis Sha'ul. He had Kin'as Hashem to fight the Pelishti.
