In order to get the primary force of the fifth cross-utterance of Jesus, we must note its setting: "Jesus knowing that all things were now accomplished, that the scripture might be fulfilled, said, I thirst" (John 19:28). The reference is to Psalm 69 - a Messianic psalm that describes so graphically His passion. In it the spirit of prophecy had declared, "They gave me poison for food, and for my thirst they gave me sour wine to drink" (v. 21). This remained yet unaccomplished. The predictions of the previous verses had already received fulfillment. He had sunk in the "deep mire" (v. 2); He had been "hated without a cause" (v. 4); He had "borne reproach and shame" (v. 7); He had "become a stranger unto his brethren" (v. 8); He had become "a proverb" to His revilers, and "the song of the drunkards" (vv. 11, 12); He had "cried unto God" in His distress (vv. 17-20) - and now there remained nothing more than the offering him the drink of vinegar and gall, and in order to fulfill this he cried "I thirst."
How completely self-possessed the Savior was! He had hung on that cross for six hours and had passed through unparalleled suffering, yet His mind is clear and His memory unimpaired. He had before Him, with perfect distinctness, the whole truth of God. He reviewed the entire scope of Messianic prediction. He remembers there is one prophetic scripture unaccomplished. He overlooked nothing. What a proof is this that He was divinely superior to all circumstances!
Adapted from The Seven Sayings of the Saviour on the Cross, 5. The Word of Suffering, by A.W. Pink.