1 John 4:1
Beloved, do not believe every spirit, but try the spirits, whether they be from God; because many false prophets are gone forth into the world.
Revelation 2:2
I know your works, and your labor, and your patience; and that you can not bear those who are evil: and you have tried those who say they are Apostles, and are not, and have found them liars;
Revelation 2:25
Nevertheless, what you have, hold fast till I come.
Revelation 3:3
Remember, therefore, how you have received and heard, and hold fast, and reform: therefore, unless you are watchful, I will come upon you as thief, and you shall not know what hour I will come upon you.
Revelation 3:11
I come quickly: keep that which you have, that no man take your crown.