Peter begins to warn the believers about false teachers.
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. AT: “For the things that we saw make this prophetic word more sure” (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/figs-activepassive)
Here the word “we” refers to all believers, including Peter and his readers. (See: rc://en/ta/man/translate/figs-inclusive)
This refers to the Old Testament. AT: “the scriptures, which the prophets spoke,” (See: rc://en/ta/man/translate/figs-explicit) (See: rc://en/ta/man/translate/figs-synecdoche)
Peter instructs the believers to pay close attention to the prophetic message.
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/translate/figs-simile)
“Hearts” here is a metonym for “thoughts and intentions.” 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. AT: “the morning star becomes supremely important in your thinking and the way you act” (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-metonymy)
The “morning star” refers to the planet Venus, which sometimes rises just before the sun and indicates that daybreak is near.
“Most importantly, you must understand”
Possible meanings are 1) the prophets did not make their prophecies on their own or 2) people must rely on the Holy Spirit to understand the prophecies or 3) people must interpret the prophecies with the help of the entire Christian community of believers.
Peter speaks of the Holy Spirit helping the prophets to write what God wanted them to write as if the Holy Spirit was carrying them from one place to another. AT: “men spoke from God as the Holy Spirit directed them” (See: rc://en/ta/man/translate/figs-metaphor)