They kept the matter
What the rising
From the dead
καὶ τὸν λόγον ἐκράτησαν πρὸς ἑαυτοὺς συνζητοῦντες τί ἐστιν τὸ ἐκ νεκρῶν ἀναστῆναι.
This is another unique passage of Mark, who tended to point out how these 3 trusted disciples, Peter, James, and John, were confused and still did not understand what was happening. Mark said that the 3 apostles were able to keep this matter quiet among themselves (καὶ τὸν λόγον ἐκράτησαν πρὸς ἑαυτοὺς). However, they questioned or discussed this among themselves (συνζητοῦντες) what the rising from the dead (τί ἐστιν τὸ ἐκ νεκρῶν ἀναστῆναι) was all about.
He found them
καὶ ἐλθὼν πάλιν εὗρεν αὐτοὺς καθεύδοντας, ἦσαν γὰρ αὐτῶν οἱ ὀφθαλμοὶ βεβαρημένοι.
This is almost word for word in Mark, chapter 14:40, but there is an addition about the apostles being embarrassed and not able to say anything. In Luke, chapter 22, and John, chapter 22, there is nothing more about these 2nd and 3rd visits of Jesus. Matthew and Mark recount that Jesus again came (καὶ ἐλθὼν πάλιν) and found his 3 disciples sleeping (εὗρεν αὐτοὺς καθεύδοντας), because their eyes were heavy or overburdened (ἦσαν γὰρ αὐτῶν οἱ ὀφθαλμοὶ βεβαρημένοι). This was the 2nd time that he found his 3 trusted disciples sleeping. There were no excuses, except that they were tired. They had failed to stay awake and be vigilant.