That ye may be mindful of the words - Of the doctrines, the truths; the prophetic statements. Jude Jude 1:18 says that it had been foretold by the apostles, that in the last days there would be scoffers. Peter refers to the instructions of the apostles and prophets in general, though evidently designing that his remarks should bear particularly on the fact that there would be scoffers.
Which were spoken before by the holy prophets - The predictions of the prophets before the advent of the Saviour, respecting his character and work. Peter had before appealed to them 2 Peter 1:19-21, as furnishing important evidence in regard to the truth of the Christian religion, and valuable instruction in reference to its nature. See the notes at that passage. Many of the most important doctrines respecting the kingdom of the Messiah are stated as clearly in the Old Testament as in the New Testament (compare Isaiah 53:1-12), and the prophecies therefore deserve to be studied as an important part of divine revelation. It should be added here, however, that when Peter wrote there was this special reason why he referred to the prophets, that the canon of the New Testament was not then completed, and he could not make his appeal to that. To some parts of the writings of Paul he could and did appeal 2 Peter 3:15-16, but probably a very small part of what is now the New Testament was known to those to whom this epistle was addressed.
And of the commandment of us the apostles of the Lord and Saviour - As being equally entitled with the prophets to state and enforce the doctrines and duties of religion. It may be observed, that no man would have used this language who did not regard himself and his fellow apostles as inspired, and as on a level with the prophets.