There follows: And they went out quickly, and fled from the sepulchre, for they trembled and were amazed.
(de Con. Evan. iii. 24.) We may however enquire how Mark can say this, when Matthew says, they departed quickly from the sepulchre with fear and great joy, and did run to bring his disciples word, (Matt. 28:8) unless we understand it to mean, that they did not dare to say a word to any of the Angels themselves, that is, to answer the words which they had spoken to them; or else to the guards whom they saw lying there; for that joy of which Matthew speaks is not inconsistent with the fear which Mark mentions. For we ought to have understood that both feelings were in their minds, even though Matthew had not mentioned the fear. But since he has also said that they came out with fear and great joy, he does not allow room for any question to be raised.
(de Con. Evan. iii. 24.) We may however enquire how Mark can say this, when Matthew says, they departed quickly from the sepulchre with fear and great joy, and did run to bring his disciples word, (Matt. 28:8) unless we understand it to mean, that they did not dare to say a word to any of the Angels themselves, that is, to answer the words which they had spoken to them; or else to the guards whom they saw lying there; for that joy of which Matthew speaks is not inconsistent with the fear which Mark mentions. For we ought to have understood that both feelings were in their minds, even though Matthew had not mentioned the fear. But since he has also said that they came out with fear and great joy, he does not allow room for any question to be raised.
Source: Catena Aurea by Aquinas