John 19:31-34

Now it was the day of Preparation, and the next day was to be a special Sabbath. Because the Jewish leaders did not want the bodies left on the crosses during the Sabbath, they asked Pilate to have the legs broken and the bodies taken down. The soldiers therefore came and broke the legs of the first man who had been crucified with Jesus, and then those of the other. But when they came to Jesus and found that he was already dead, they did not break his legs. Instead one of the soldiers pierced Jesus' side with a spear, bringing a sudden flow of blood and water.

Now it was the day of Preparation 
John 19:14  It was the day of Preparation of the Passover; it was about noon. "Here is your king," Pilate said to the Jews.
John 19:42  Because it was the Jewish day of Preparation and since the tomb was nearby, they laid Jesus there.

Because the Jewish leaders did not want the bodies left on the crosses during the Sabbath 
Deuteronomy 21:22-23  If someone guilty of a capital offense is put to death and their body is exposed on a pole, you must not leave the body hanging on the pole overnight. Be sure to bury it that same day, because anyone who is hung on a pole is under God's curse. You must not desecrate the land the LORD your God is giving you as an inheritance. 
Joshua 8:29  He impaled the body of the king of Ai on a pole and left it there until evening. At sunset, Joshua ordered them to take the body from the pole and throw it down at the entrance of the city gate. And they raised a large pile of rocks over it, which remains to this day. 
Joshua 10:26-27  Then Joshua put the kings to death and exposed their bodies on five poles, and they were left hanging on the poles until evening. At sunset Joshua gave the order and they took them down from the poles and threw them into the cave where they had been hiding. At the mouth of the cave they placed large rocks, which are there to this day. 

The soldiers therefore came and broke the legs of the first man who had been crucified with Jesus, and then those of the other 
John 19:18  There they crucified him, and with him two others--one on each side and Jesus in the middle.

Instead one of the soldiers pierced Jesus' side with a spear 
Zechariah 12:10  "And I will pour out on the house of David and the inhabitants of Jerusalem a spirit of grace and supplication. They will look on me, the one they have pierced, and they will mourn for him as one mourns for an only child, and grieve bitterly for him as one grieves for a firstborn son." 
Revelation 1:7  "Look, he is coming with the clouds," (Daniel 7:13) and, "every eye will see him, even those who pierced him;" and all peoples on earth "will mourn because of him." (Zechariah 12:10) So shall it be! Amen. 

bringing a sudden flow of blood and water 
1 John 5:6  This is the one who came by water (Jesus' baptism) and blood (Jesus' death)--Jesus Christ. He did not come by water only, but by water and blood. And it is the Spirit who testifies, because the Spirit is the truth.

(parentheses are mine)

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