Jamieson, Fausset and Brown on John 19:28-30

28-30. 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 (Psa 22:15).

that the scripture--(Psa 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 Joh 19:24.

and they--"one of them," (Mt 27:48).