The things that Peter and the other apostles saw, which he described in the previous verses, confirm what the prophets spoke. This can be stated in active form. Alternate translation: "For the things that we saw make this prophetic message more sure" (See: [[rc://en/ta/man/jit/figs-explicit]] and [[rc://en/ta/man/jit/figs-activepassive]])
Peter compares the prophetic word to a lamp that gives light in the dark until light comes in the morning. The coming of morning is a reference to Christ's coming. (See: [[rc://en/ta/man/jit/figs-simile]])
Peter speaks of Christ as the "morning star," which indicates that daybreak and the end of darkness is near. Christ will bring light into the hearts of believers, ending all doubt and bringing full understanding of who he is. Here "hearts" is a metonym for people's minds. Alternate translation: "Christ shines his light into your hearts like the morning star shines its light into the world" (See: [[rc://en/ta/man/jit/figs-metaphor]] and [[rc://en/ta/man/jit/figs-metonymy]])