Theophylact of Ohrid

"But go, tell His disciples and Peter." He separates Peter from the disciples either as the chief one, naming him specially apart from the others by preeminence, or for this reason: since Peter had denied, if the women had said they were commanded to announce only to the disciples, he would have said: I denied Him, therefore I am no longer His disciple, and so the Lord has rejected me and been disgusted with me. …

Commentary on Mark ↗

Augustine of Hippo

By saying, He will go before you into Galilee, there shall ye see him, as he said unto you, he seems to imply, that Jesus would not show Himself to His disciples after His resurrection except in Galilee, which showing of Himself Mark himself has not mentioned. …

Catena Aurea by Aquinas ↗

Gregory the Dialogist

"But go, tell His disciples and Peter that He goes before you into Galilee." We must ask why, when the disciples are named, Peter is designated by name. But if the angel had not expressly named him who had denied his Master, he would not have dared to come among the disciples. Therefore he is called by name, lest he despair because of his denial. In this matter we must consider why Almighty God permitted him whom He had determined to place over the whole Church to fear the voice of a servant girl and to deny himself. …

Forty Gospel Homilies, Homily 21 ↗

Bede

But go, tell his disciples and Peter that he is going ahead of you into Galilee. We must ask why Peter is specifically named when mentioning the disciples. But if the angel had not explicitly named him, he who had denied the Master would not have dared to come among the disciples. Therefore, he is called by name so that he may not despair because of his denial. In this matter, we must consider why Almighty God allowed the one whom he had planned to place over the entire Church to fear the voice of a maid and deny himself. …

On the Gospel of Mark ↗