What is the significance of the Lord saying at the cross, ‘I thirst’?

This text is from a transcript of a talk by David Gooding, entitled ‘Four Journeys to Jerusalem’ (2009).

The question of, 'I thirst,' is a Psalm, is it not? It is from Psalm 69: 'In my thirst they gave me vinegar to drink' (Psalm 69:21 RV).

Now, the question of whether it was a mockery, or a mercy, is debated. When it came to offering him wine mingled with myrrh, which in those far off days was an attempt to numb the system and alleviate the pain, they offered it to him, and he put it to his lips but then refused to drink it (Matthew 27:34). He acknowledged their kindness in offering it but wouldn't drink something that would numb the pain. But it was an ordinary custom at crucifixions to have sour vinegar (sour wine at any rate) because the thirst was colossal. As a mercy, they used that sour vinegar to refresh the lips of the people being crucified.

Whether therefore it was a mercy, or a mockery, who knows? And I think you have to decide that in the process of answering your question. I myself think that the first thing is that the giving of the sour wine was initiated by our Lord's own statement. He, 'knowing all things were now accomplished . . . ' (see John 19:28). There was this other thing that was not yet accomplished. They had not yet given him vinegar to drink, and therefore he said, 'I thirst.' And in response to that, they gave him vinegar to drink.

Now, some people say, 'But that is altogether a small thing. That would be a very artificial thing to think that our Lord said it just to get them to give him vinegar to drink; that would be too artificial.' And so people say that when he said 'I thirst' he was 'thirsty for the salvation of men', or 'thirsting to please God'. It so happened that they gave him vinegar to drink, and that fulfilled the Scripture, but the, 'I thirst,' was thirsting for the souls of men, or something.

Well, it could be. My own thinking would start, as usual, from the literal. And if he said, 'I thirst,' and you say, 'Is that literal or metaphorical?' I would have said, in the first place, it was very literal. If you had been crucified for three hours, you would run up a tremendous fever and thirst. But it could also be metaphorical, and that I would not deny. 'I thirst to please God. I thirst for the souls of men,' and the soldiers thought it was literal thirst and offered him a drink. But it is that offering him a drink and the thirst that the Psalm ('the writing') is talking about isn't it?