What does Mark 15:46 mean?
The cave where Joseph places Jesus is Joseph's own (Matthew 27:60). Burial practices in the area require the body to lay in a tomb for a year until the flesh is gone from the bones. The bones are then placed in a permanent grave, often in a stone box or ossuary. Joseph carved the tomb out of the stone—more likely had workers do so—and it has never been used (John 19:41).Mark mentions Joseph and the linen shroud. John adds that Nicodemus brings "a mixture of myrrh and aloes, about seventy-five pounds in weight" (John 19:39). John also says they bury Jesus in the "burial custom of the Jews" (John 19:40). This would include washing Jesus' body before wrapping it in linen. There is a foolish conspiracy theory that states Mary Magdalene must be Jesus' wife because she would not have otherwise gone to the tomb to properly prepare His body for burial. That is, she wouldn't have washed it if this was not her husband. John, however, suggests that the men wash Jesus' body before wrapping it. The women merely come to honor Jesus with more burial spices than those Nicodemus can quickly arrange.
For this night, the stone over the entry suffices to seal the tomb. The next morning, the chief priests and Pharisees will approach Pilate and ask for one more favor (Matthew 27:62–66). They remember that Jesus promised He would rise from the dead (John 2:19). Although they don't believe it, they fear His disciples will steal His body and claim the empty tomb proves His resurrection. So the Jewish leaders ask Pilate to seal the stone and set guards over the tomb. The process of sealing would have involved wrapping a cord where the stone meets the rock face and covering the crack with wax. It would be impossible to get into the tomb without breaking the wax seal.
Of course, the disciples don't open the tomb, but three days later, the stone is rolled away and Jesus is gone (Mark 16:1–4). The guards have failed (Matthew 28:1–15). The women who have come to complete the burial procedure are met with an earthquake and an angel which frighten the guards into blacking out. When the guards finally regain their wits, they report what they have seen to the chief priests. The chief priests confer with the elders and decide to bribe the soldiers into claiming they fell asleep and the disciples took Jesus' body. Why Pilate apparently didn't execute the soldiers for dereliction of duty is uncertain. Possibly, it's because their lie also covered Pilate's inability to keep a dead man buried.
