Jesus, knowing that all things were now accomplished. John purposely passes by many things which are related by the other three Evangelists. He now describes the last act, which was an event of the greatest importance.When John says that a vessel was placed there, he speaks of it as a thing that was customary. There has been much controversy on this subject; but I agree with those who think (and, indeed, the custom is proved by histories) that it was a kind of beverage usually administered for the purpose of accelerating the death of wretched malefactors, when they had undergone sufficient torture [1] Now, it ought to be remarked, that Christ does not ask any thing to drink till all things have been accomplished; and thus he testified his infinite love towards us, and the inconceivable earnestness of his desire to promote our salvation. No words can fully express the bitterness of the sorrows which he endured; and yet he does not desire to be freed from them, till the justice of God has been satisfied, and till he has made a perfect atonement. [2] But how does he say, that all things were accomplished, while the most important part still remained to be performed, that is, his death? Besides, does not his resurrection contribute to the accomplishment of our salvation? I answer, John includes those things which were immediately to follow. Christ had not yet died: and had not yet risen again; but he saw that nothing now remained to hinder him from going forward to death and resurrection. In this manner he instructs us, by his own example, to render perfect obedience, that we may not think it hard to live according to his good pleasure, even though we must languish in the midst of the most excruciating pains. That the Scripture might be fulfilled. From what is stated by the other Evangelists, (Matthew 27:48; Mark 15:23, 36; Luke 23:36,) it may readily be concluded that the passage referred to is Psalm 69:21, They gave me gall for my food, and in my thirst they gave me vinegar to drink. It is, undoubtedly, a metaphorical expression, and David means by it, not only that they refused to him the assistance which he needed, but that they cruelly aggravated his distresses. But there is no inconsistency in saying that what had been dimly shadowed out in David was more clearly exhibited in Christ: for thus we are enabled more fully to perceive the difference between truth and figures, when those things which David suffered, only in a figurative manner, are distinctly and perfectly manifested in Christ. To show that he was the person whom David represented, Christ chose to drink vinegar; and he did so for the purpose of strengthening our faith. I thirst. Those who contrive a metaphorical meaning for the word thirst, as if he meant that, instead of a pleasant and agreeable beverage, they gave him bitterness, as if they intended to flay his throat, [3] are more desirous to be thought ingenious than to promote true edification; and, indeed, they are expressly refuted by the Evangelist, who says that Christ asked for vinegar when he was near death; from which it is evident that he did not desire any luxuries. [4]

Footnotes

1 - "On dispute diversement de ceci; mais je m'accorde a l'opinion de ceux qui disent (comme aussi I'llsage enest approuvee par les histoires) que e'estoit une sorte de bruvage, duquel coustumierement on usoit pour avaneer la mort des poures malfaiteurs, apres qu'ils avoyent este assez tormentez."

2 - The French copy gives an additional clause to this sentence: -- "Comme s'il s'estoit oublid jusqu'k ce qu'ayant satisfait au payement de nos offenses, il declare qu'il n'est pas insensible, mais que l'amour qu'il nous portoit a surmontd toutes les angoisses;" -- "As if he had forgotten his own concerns till he had given full satisfaction for our sins, he declares that he is not incapable of feeling, but that the love which he bore to us rose superior to all the pains which he endured."

3 - "Comme s'il vouloit dire qu'au lieu de bruvage doux et aimable, on luy a donna de l'amertume, cornroe pour lug escorcher le gosicr."

4 - "En quoy fi' appert qu'il n'estoit question de nulles, delices."

See the notes at Matthew 27:46-50.
That the scripture might be fulfilled, saith, I thirst - See Psalm 69:21. Thirst was one of the most distressing circumstances attending the crucifixion. The wounds were highly inflamed, and a raging fever was caused, usually, by the sufferings on the cross, and this was accompanied by insupportable thirst. See the notes at Matthew 27:35. A Mameluke, or Turkish officer, was crucified, it is said in an Arabic manuscript recently translated, on the banks of the Barada River, under the castle of Damascus. He was nailed to the cross on Friday, and remained until Sunday noon, when he died. After giving an account of the crucifixion, the narrator proceeds: "I have heard this from one who witnessed it; and he thus remained until he died, patient and silent, without wailing, but looking around him to the right and the left, upon the people. But he begged for water, and none was given him; and the hearts of the people were melted with compassion for him, and with pity on one of God's creatures, who, yet a boy, was suffering under so grievous a trial. In the meantime the water was flowing around him, and he gazed upon it, and longed for one drop of it; and he complained of thirst all the first day, after which he was silent, for God gave him strength" - Wiseman's Lectures, pp. 164, 165, ed.

I thirst - The scripture that referred to his drinking the vinegar is Psalm 69:21. The fatigue which he had undergone, the grief he had felt, the heat of the day, and the loss of blood, were the natural causes of this thirst. This he would have borne without complaint; but he wished to give them the fullest proof of his being the Messiah, by distinctly marking how every thing relative to the Messiah, which had been written in the prophets, had its complete fulfillment in him.

(9) After this, Jesus knowing that all things were now accomplished, that the scripture might be fulfilled, saith, I thirst.
(9) Christ when he has taken the vinegar, yields up the Spirit, indeed drinking up in our name that most bitter and severe cup of his Father's wrath.

After this,.... After he had committed his mother to the care of John, which was about the sixth hour, before the darkness came over the land: and three hours after this was the following circumstance, which was not without the previous knowledge of Christ:
Jesus knowing that all things were now accomplished; or just upon being accomplished, were as good as finished; and as they were to be, would be in a very short time; even all things relating to his sufferings, and the circumstances of them, which were afore appointed by God, and foretold in prophecy, and of which he had perfect knowledge:
that the Scripture might be fulfilled: might appear to have its accomplishment, which predicted the great drought and thirst that should be on him, Psalm 22:15 and that his enemies at such a time would give him vinegar to drink, Psalm 69:21
saith, I thirst; which was literally true of him, and may be also understood spiritually of his great thirst and eager desire after the salvation of his people.

After this, Jesus knowing that all things were now accomplished--that is, the moment for the fulfilment of the last of them; for there was one other small particular, and the time was come for that too, in consequence of the burning thirst which the fevered state of His frame occasioned (Psalm 22:15).
that the scripture-- (Psalm 69:21).
might be fulfilled saith, I thirst. Now there was set a vessel full of vinegar--on the offer of the soldiers' vinegar, see on John 19:24.
and they--"one of them," (Matthew 27:48).