2 Peter 1:20

18 And this voice which came from heaven we heard, when we were with him in the holy mount.

19 We have also a more sure word of prophecy; 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:

Knowing this first, that no prophecy of the scripture is of any private interpretation.

21 For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.

Do read the surrounding verses too, because the context often says more than a single verse.

Compare

BSB
Above all, you must understand that no prophecy of Scripture comes from one’s own interpretation.
KJV
Knowing this first, that no prophecy of the scripture is of any private interpretation.
WEB
knowing this first, that no prophecy of Scripture is of private interpretation.
ASV
knowing this first, that no prophecy of scripture is of private interpretation.
DARBY
knowing this first, that [the scope of] no prophecy of scripture is had from its own particular interpretation,
BLB
knowing this first, that every prophecy of Scripture is not of its own interpretation.
ÅB
ettersom dere først og fremst vet dette: intet profetord i Skriften oppstår ved profetens egen utlegging;
OTB
Men vit dette først av alt, at ingen profeti i Skriften kommer fra noens egen tolkning,
B1930
idet I først og fremst vet dette at intet profetord i Skriften er gitt til egen tydning;

Study notes (Tyndale)

Original text and word study