Deuteronomy 18:21

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

1 Thessalonians 5:24

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

1 John 4:1-3

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

Revelation 2:2

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