1 Peter 1:24-25

24 For,

“ALL FLESH IS LIKE GRASS,

AND ALL ITS GLORY LIKE THE FLOWER OF GRASS.

THE GRASS WITHERS,

AND THE FLOWER FALLS OFF,

25 BUT THE WORD OF THE LORD ENDURES FOREVER.”

And this is the word which was preached to you.

In these verses Peter quotes from Isaiah 40:6-8, in order to explain the living and enduring word of God that is planted in them to give them eternal life. This life in them is not like the grass or the flowers that wither away, but is of an enduring, everlasting substance.