Of David himself, before he was anointed.
1. Christ's young soldier speaks, on his coming to the faith. “The Lord is my light, and my salvation: whom shall I fear?”. The Lord will give me both knowledge of Himself, and salvation: who shall take me from Him? “The Lord is the Protector of my life: of whom shall I be afraid?” The Lord will repel all the assaults and snares of mine enemy: of no man shall I be afraid.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)