Deuteronomy 18:21

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

1 Thessalonians 5:24

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

1 John 4:1-3

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

Revelation 2:2

I know thy works, and thy labor, and thy patience, and that thou canst not bear them who are evil; and thou hast tried them who say they are apostles, and are not; and hast 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 calleth you, who also will do it.
1 John 4:1
Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets have gone out into the world.
Revelation 2:2
I know thy works, and thy labor, and thy patience, and that thou canst not bear them who are evil; and thou hast tried them who say they are apostles, and are not; and hast found them liars: