The Matthew passage from day 35 overlaps with John 18:1-18 in that both deal with Jesus' betrayal and arrest. In verses 15-18 of this passage we see Jesus' foretelling of Peter's denial unfold. It is interesting to see how there is another disciple known to the high priest, who was able to get them in. We know nothing of his connection beyond this, but he appears to make no move to deny his association. Peter (presumably with a Galilean accent) was spotted as so, but denied it.
We might claim we won't deny Jesus, but many of us falter when the opportunity to own up to our faith comes up. This short passage reminds us that we need to be slow to speak of the strength of our faith, for when push comes to shove, no one is invincible in their faith. We'd like to think so, but it is more honest to recognise when our faith is weak, and seek for Christ to help make it stronger.