Charles Spurgeon Commentary 2 Peter 1:19

"And we have the word of prophecy [made] more sure; whereunto ye do well that ye take heed, as unto a lamp shining in a dark place, until the day dawn, and the day-star arise in your hearts:" — 2 Peter 1:19 (ASV)

Whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts:

You already have the assurance of the Word itself; you must build upon that, and upon that alone; but you will have a "day dawn" and a "day star" added to that in your own hearts. We have the witness within us now: The Spirit himself beareth witness with our spirit, that we are the children of God; and those things which we have received by faith, we have now proved to be true by their effect upon our own souls. We know the light now because we walk in it; we know it to be light, for it has enlightened us.

We have also a more sure word of prophecy;

Can anything be more sure than that which an eyewitness sees?

Well, Peter says that this prophetic Book, in which Holy Scripture is stored up, is better to us than if we had even seen Christ himself. If any one thing is more sure than another, it is this blessed book—the revelation of the Christ of God.

We have also a more sure word of prophecy;

Surely, nothing could be more sure than the evidence presented to the apostles in the holy mount. Yet Peter thus writes to express his utmost confidence in the Word of God. Surer than the light he saw, which dazzled him; surer than the voice he heard, which he never failed to remember, and to which he ever bore unfaltering witness; surer even than these things is that divine Book which is still preserved to us: We have also a more sure word of prophecy;.