Be watchful, and strengthen the things which remain, that are ready to die, for I have not found your works perfect before God.
Revelation 3:2
Surrounding context
3:1 "And to the angel of the church in Sardis write, "These things says He who has the seven Spirits of God and the seven stars: "I know your works, that you have a name that you are alive, but you are dead.
3:2 Be watchful, and strengthen the things which remain, that are ready to die, for I have not found your works perfect before God.
3:3 Remember therefore how you have received and heard; hold fast and repent. Therefore if you will not watch, I will come upon you as a thief, and you will not know what hour I will come upon you.