Go quickly and tell his disciples, "He has been raised from the dead,"
the angel of the Lord tells the women when they see the tomb empty;
Go and tell my brothers to go to Galilee,
Jesus himself tells them as he meets them on the way and they worship him:
there they will see me.
The last we heard of his disciples, his brothers, in Matthew's gospel, is their failure to stay awake with him at Gethsemane, Judas Iscariot's betrayal of him, and Simon Peter's denial of all knowledge of him. They were absent at Golgotha.
On the other hand,
many women were there, looking on from distance,
women who 'had followed Jesus from Galilee and ministered to him'
The way Matthew tells the story means he must want us to see the contrast between the disciples who had abandoned him or worse, and the women followers who kept watch while he died, who were there when Joseph of Arimathea laid the body of Jesus in the tomb, and were the first to visit the tomb.
These women's faithfulness, their vigil at the tomb, meant that they were there; available to be sent to call the disciples together, with the news of his resurrection and the promise that they would see him in Galilee.
Matthew concludes with the disciples gathered on the mountain in Galilee, with the risen Lord Jesus sending them out with all authority to make disciples of all nations, baptising and teaching them to do as he commanded. Thus he sends the disciples out, to continue his mission, in effect to form the church---the very disciples who failed him now brought together as his apostles, brought together however through the mission he gave to Mary Magdalene and the other Mary.
Commissioned by the angel to take the news of Jesus' resurrection from the dead to his disciples, commanded by Jesus himself to tell his brothers to gather in Galilee to see him, these two women are the first to hear of his resurrection,and the first to adore Jesus as Lord.
Originally, historically, Matthew is saying, faith in Jesus as Lord already existed in these women---before the apostles ever began to preach. Indeed, these women's recognition of Jesus as Lord happened on their way to calling the disciples together to become the apostolic community.
Nothing much is recorded in the gospels that does not have a further dimension, a prophetic trajectory. The gathering of the disciples on the mountain to receive Christ's authority to baptize and teach is Matthew's way of telling us that the apostles and their successors in the church have the risen Lord's authority to preach and baptize.
But what Matthew is also telling us is that the apostolic community was constituted, so to speak, by receiving the news of the resurrection and the command to regroup from someone else, from these women in fact, who prayed as he died, who kept vigil by his tomb, who met him on the way, who had seen the risen Lord for themselves.
Those who preach in the Lord's name, with his authority, do so in response to a summons from people who have already encountered the risen Lord Jesus. One of the things a preacher learns, one of the things I have begun to learn in forty years of preaching, is that a preacher has nothing to tell people that they have not already seen (beware of preachers who tell you things you have never heard before!).
There is no preaching of the resurrection which does not resonate with the faith that is already in the listeners' hearts. 'Christ is risen' is the message the authorized preachers have to proclaim; but it is a message they receive from others---from all the other disciples for whom Jesus is always already Lord.