After this, he who extracts from the Gospel narrative those statements on which he thinks he can found an accusation, makes the vinegar and the gall a subject of reproach to Jesus, saying that “he rushed with open mouth to drink of them, and could not endure his thirst as any ordinary man frequently endures it.” Now this matter admits of an explanation of a peculiar and figurative kind; but on the present occasion, the statement that the prophets predicted this very incident may be accepted as the more common answer to the objection.
For in the sixty-ninth Psalm there is written, with reference to Christ: “And they gave me gall for my meat, and in my thirst they gave me vinegar to drink.” Now, let the Jews say who it is that the prophetic writing represents as uttering these words; and let them adduce from history one who received gall for his food, and to whom vinegar was given as drink. Would they venture to assert that the Christ whom they expect still to come might be placed in such circumstances? Then we would say, What prevents the prediction from having been already accomplished?
For this very prediction was uttered many ages before, and is sufficient, along with the other prophetic utterances, to lead him who fairly examines the whole matter to the conclusion that Jesus is He who was prophesied of as Christ, and as the Son of God.
Source: Against Celsus (New Advent)