my God. Two names for God, Elohim and El, are used in this first sentence—the first a plural form, the second singular — possibly intimating some awareness of the Godhead.

thirsteth for thee. Note that, even in a parched desert, David's thirst was not for water, but for the Lord. His longing was not for a return to his home and throne, but for God, to know again His power and His glory (Psalm 63:2).

the night watches. David's meditation during the night centered on the Lord. Therefore, it was early in the morning that he would seek His presence (Psalm 63:1).

lower parts of the earth. This striking phrase is used also in Psalm 139:15, Isaiah 44:23, Ezekiel 31:14, 16, 18, and 32:18, 24. In the Ezekiel passages it is rendered “nether parts of the earth,” in Psalm 139:15 “lowest parts of the earth,” but the Hebrew is the same. The equivalent phrase in Greek is found in Ephesians 4:9. Depending on context, it can refer either to the great subsurface depths of the earth or (especially in the Ezekiel and Ephesian passages) to the great pit (sheol, hades) in the center of the earth where the spirits of the dead are incarcerated for a time.