John Gill Commentary Psalms 148:6

"He hath also established them for ever and ever: He hath made a decree which shall not pass away." — Psalms 148:6 (ASV)

He has also stablished them for ever and ever
The angels are made immortal, and shall never die; and they are confirmed in their state of happiness by Christ, and shall always continue in it; the hosts of heaven being created by him, consist in him, and will remain as long as the world does; hence the duration and never-failing state of other things, even of good men and their felicity, are expressed by them; see (Psalms 72:5Psalms 72:7) (Psalms 89:36Psalms 89:37) ;

he has made a decree which shall not pass ;
concerning those creatures and their duration, which shall never pass away, or be frustrated or made void; but shall always continue and have its sure and certain effect; see (Jeremiah 31:35Jeremiah 31:36) (33:25) ; and is true of every decree of God, which is eternal and not frustrable, and is always fulfilled, (Isaiah 14:27) (25:1) (46:10) .