Why did he say "Urah Kevodi"?
Rashi: I will not sleep until three hours of the day in my honor, like other kings do.
Radak: After You will save me from them, I will sing to You vocally and with a Kli. I will tell Nafshi, i.e. Kevodi, to compose a Shir.
Malbim: Then, all emotions of his Nefesh, his honor, which dwelled in the earth until now, should arouse.
Why did he say "Urah ha'Nevel v'Chinor"?
Rashi: Wake me, you lyre and harp suspended over my bed, open to the north. When midnight comes, the north wind begins to blow, and [they play, and] David rises and engages in Torah.
Radak: He metaphorically tells them to waken (or arouse) themselves [and play].
Malbim: The lyre and harp, which were silent until now, should arouse with pleasant songs.
Why did he say "A'ira Shachar"?
Rashi (from Bamidbar Rabah 15:16): I wake [before] the morning (dawn); the morning does not wake me. Taz (OC 1:2) - it is an attribute to initiate arousal from below, and then there is arousal from above to reach a higher level 1 . David was at such a level that he did not need the arousal from above!
Radak #1: [He tells the lyre and harp to arouse themselves] when I arouse my Nefesh to sing every morning.
Radak #2: When I wake from sleep in the morning to thank Your name with them, I tell them to waken.
Malbim: Now the 'sun' of my success, which was dark until now, began shining. I.e. now Sha'ul himself recognized my honor, and said "Tzadik Atah Mimeni; ... Yadati Ki Maloch Timloch" (Shmuel I, 24:17, 20).
Yuma 39a: "V'Hiskadahtem vi'Hyisem Kedoshim" (Vayikra 20:7) - man sanctifies himself a little, from below, and [Shamayim] sanctifies him greatly, from above. Man sanctifies himself in this world, from, and [Shamayim] sanctifies him in the world to come.
