Deuteronomy 18:21

And, when thou shalt say in thy heart, - In what manner shall we know the word which Yahweh hath not spoken!?,

1 Thessalonians 5:24

Faithful, is he that is calling you, - who, also will perform.

1 John 4:1-3

Beloved! not in every spirit, believe ye, but test 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 toil, and endurance, and that thou canst not bear bad men, and thou hast tried them who were affirming themselves to be apostles, and they were not, and hast found them false;

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 is calling you, - who, also will perform.
1 John 4:1
Beloved! not in every spirit, believe ye, but test 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 toil, and endurance, and that thou canst not bear bad men, and thou hast tried them who were affirming themselves to be apostles, and they were not, and hast found them false;