Deuteronomy 18:21

And if you say in your heart, How shall we know the word which the LORD has not spoken?

1 Thessalonians 5:24

Faithful is he that calls you, who also will do it.

1 John 4:1-3

Beloved, believe not every spirit, but test the spirits whether they are of God: because many false prophets are gone out into the world.

Revelation 2:2

I know your works, and your labor, and your patience, and how you can not bear them who are evil: and you have tried them who say they are apostles, and are not, and have found them liars:

Treasury of Scripture Knowledge

Summary

And if thou say in thine heart, How shall we know the word which the LORD hath not spoken?

Bible References

General references

1 Thessalonians 5:24
Faithful is he that calls you, who also will do it.
1 John 4:1
Beloved, believe not every spirit, but test the spirits whether they are of God: because many false prophets are gone out into the world.
Revelation 2:2
I know your works, and your labor, and your patience, and how you can not bear them who are evil: and you have tried them who say they are apostles, and are not, and have found them liars: