57 When it was evening, there came a rich man from Arimathea, named Joseph, who was also a disciple of Jesus. 58He went to Pilate and asked for the body of Jesus; then Pilate ordered it to be given to him. 59So Joseph took the body and wrapped it in a clean linen cloth 60and laid it in his own new tomb, which he had hewn in the rock. He then rolled a great stone to the door of the tomb and went away. 61Mary Magdalene and the other Mary were there, sitting opposite the tomb.
62 The next day, that is, after the day of Preparation, the chief priests and the Pharisees gathered before Pilate 63and said, ‘Sir, we remember what that impostor said while he was still alive, “After three days I will rise again.” 64Therefore command that the tomb be made secure until the third day; otherwise his disciples may go and steal him away, and tell the people, “He has been raised from the dead”, and the last deception would be worse than the first.’ 65Pilate said to them, ‘You have a guard of soldiers; go, make it as secure as you can.’ 66So they went with the guard and made the tomb secure by sealing the stone.
"New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved." http://www.ncccusa.org/newbtu/permiss.html
In Matthew, Joseph becomes a wealthy man who is one of Jesus’ disciples. Thus, he owns the tomb in which Jesus is buried. As in Mark, the two Marys observe the burial proceedings.
Most importantly, Matthew presents a unique scene in which the chief priests and Pharisees have Pilate place a guard on the tomb in order to forestall the theft of the body. They want to prevent any claims by his disciples that Jesus was raised from the dead. The Pharisees have been notably absent throughout the passion narrative, so their sudden reappearance here is a signal that debates from Matthew’s time are at work. Matthew wants to defend against charges being aimed at his church that their claims for the resurrection of Jesus are fraudulent.