The Second Epistle of Peter was also written by the apostle Peter in the middle of the first century. It warns of false teachers who had come into the Early Church and urges Christians to be brave and patient.

2 Peter 2

2:1 But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction.