I lift my hands to you in prayer. I thirst for you as parched land thirsts for rain. ~ Psalm 143:6 (NLT)
On the last and greatest day of the Festival, Jesus stood and said in a loud voice, "Let anyone who is thirsty come to me and drink. Whoever believes in me, as Scripture has said, rivers of living water will flow from within them." ~ John 7:37-38 (TNIV)
The two sentences in Psalm 143:6 are Hebrew parallelisms. That is, they're really both saying the same thing in a slightly different way.
King David, reported to be the psalmist, pictures himself as a thirsty desert crying out to God for a drink -- not just of water but of the LORD'S renewing presence. This is a cry of desperation that can only be expressed by the metaphor of thirst.
The psalmist feels overwhelmed by his situation -- hunted (vs. 3), abandoned (vs. 4), depressed (vs. 7). Yet he prays and recalls God's faithfulness. This is what he's banking on when he says that he's thirsty for the LORD -- a fresh experience of God's faithfulness and righteousness (vs. 1).
It is no coincidence, then, that in John's gospel account Jesus declares himself the source of living water "for anyone who is thirsty" -- rivers of living water.
I lived in the deserts of the Southwest part of the US for a number of years. And when it rains in the desert it's phenomenal and mind-boggling to suddenly see rivers flowing all over the place -- rivers where you couldn't imagine anything but dry dust just a few minutes before. That which appeared so dead is suddenly quite alive. Surprise! The thirsty land drinks in as much as it can and lets the rest run off into the temporary lakes where it percolates and penetrates deeply into the ground.
Lord Jesus, I feel dried out -- overwhelmed and desperate. You know my situation. You know my frustration. I don't know how much more of this I can take. I need relief. I need a refreshing drink. I need a river! Pour yourself into me. Rehydrate my life that I might more completely trust you today. This is my prayer.