Matthew Henry Commentary John 19:31-37

"The Jews therefore, because it was the Preparation, that the bodies should not remain on the cross upon the sabbath (for the day of that sabbath was a high [day]), asked of Pilate that their legs might be broken, and [that] they might be taken away. The soldiers therefore came, and brake the legs of the first, and of the other that was crucified with him: but when they came to Jesus, and saw that he was dead already, they brake not his legs: howbeit one of the soldiers with a spear pierced his side, and straightway there came out blood and water. And he that hath seen hath borne witness, and his witness is true: and he knoweth that he saith true, that ye also may believe. For these things came to pass, that the scripture might be fulfilled, A bone of him shall not be broken. And again another scripture saith, They shall look on him whom they pierced." — John 19:31-37 (ASV)

A test was made to see if Jesus was dead. He died in less time than people crucified commonly did. This showed that He had laid down His life of His own accord. The spear ruptured the very sources of life; no human body could survive such a wound. But its solemn attestation shows there was something unique in it.

The blood and water that flowed out signified those two great benefits which all believers receive through Christ: justification and sanctification—the blood for atonement, the water for purification. They both flow from the pierced side of our Redeemer. To Christ crucified we owe the merit for our justification, and the Spirit and grace for our sanctification.

Let this silence the fears of weak Christians and encourage their hopes; both water and blood came from Jesus' pierced side, to both justify and sanctify them. The Scripture was fulfilled when Pilate did not allow His legs to be broken (Psalms 34:20). There was a type of this in the Passover lamb (Exodus 12:46). May we always look to Him, whom we, by our sins, have ignorantly and heedlessly pierced—indeed, sometimes even against our convictions and His mercies—and who shed from His wounded side both water and blood, that we might be justified and sanctified in His name.