The question of the origin of the testimony reported in Matthew 28.2-4 is particularly interesting, because Matthew describes events that seem to have taken place before the women arrived at the tomb:
“And behold, there was a great earthquake; for an descended from heaven, came and rolled back the stone, and sat on it. His appearance was like lightning, and his like snow. The guards trembled for fear and became like dead men.” (Matthew 28.2-4)
Now, if we compare the four Gospels, the women already find the stone rolled away when they arrive (Mark 16.4 ; Luke 24.2 ; John 20.1). It is therefore probable that they did not witness the angel’s descent or the moving of the stone.
The guards: the most probable witnesses
Matthew’s text itself provides a clue. A few verses later, the guards go to the chief priests to report what had happened:
“Some of the guard came into the city and reported to the chief priests all that had happened.” (Matthew 28.11)
These soldiers are therefore the only explicitly mentioned witnesses of the angel’s descent, of the earthquake and of their own terrified reaction. It is very likely that Matthew obtained this information indirectly, through people who knew of their report.
A transmission through the Jewish authorities?
Matthew is also the only evangelist to report the episode of the setting of the guard (Matthew 27.62-66) as well as the attempt of the religious authorities to bribe the soldiers to spread another version of the facts (Matthew 28.12-15).
This detail suggests that some of the information came from circles close to the or from people who had access to these discussions. We also know that some members of the council were favorable to Jesus, such as Joseph of Arimathea (Matthew 27.57 ; Luke 23.50-51) or Nicodemus (John 3.1-2 ; John 19.39). They could have served as relays of information.
Did the women see the angel roll away the stone?
Some harmonizations propose that the women witnessed part of the scene. However, this hypothesis is hard to reconcile with Mark, Luke and John, who present the stone as already moved when they arrived (Mark 16.4 ; Luke 24.2 ; John 20.1).
Most commentators therefore consider that Matthew is making a narrative flashback here in order to explain how the stone was rolled away before the women arrived.
Conclusion
The most probable human witness of the events described in Matthew 28.2-4 is the guard posted in front of the tomb. It is, moreover, the only category of witnesses explicitly present at the moment when the angel descends and the stone is moved. The women then discover the consequences of this event, but not the event itself. Matthew most likely obtained this information through the indirect testimony of the guards or through people linked to the religious authorities who had received their report (Matthew 28.11-15).