Matthew
Matthew 17:23ESV·traditional attribution

and they will kill him, and he will be raised on the third day.” And they were greatly distressed.

Matthew Henry Presbyterian @wholebiblehenry

Christ here foretels his own sufferings; he began to do it before (Mat 16:21); and, finding that it was to his disciples a hard saying, he saw it necessary to repeat it. There are some things which God speaketh once, yea twice, and yet man perceiveth it not. Observe here, 1. What he foretold concerning himself - that he should be betrayed and killed.

Commenting on Matthew 17:22-23

John Gill Reformed Baptist @doctorgill

And they shall kill him,.... Put him to death, with the death of the cross; for the angels in rehearsing these words, affirm, that Christ told his disciples at this time, and in this place, whilst they were in Galilee, that he should be crucified, Luk 24:7.

Albert Barnes Presbyterian @notesbybarnes

Verse 23. And they shall kill him, and the third day he shall be raised again, See . Mark and Luke add, that they understood not that saying, and it was hid from them, and they were afraid to ask him. The reasons of this may have been: (1.) They were strongly attached to him, and were exceedingly sorry (Matthew) at any intimation that the was soon to leave them.