Galatians 1:9

As we said before, so even now I say again, if any one preaches to you any other gospel than that which you have received, let him be accursed.

Romans 16:17

Now I beseech you, brethren, to mark those who make divisions and cause offenses in opposition to the teaching which you have learned, and avoid them.

2 Corinthians 1:17

In forming this purpose, did I, therefore, behave with levity? or do I purpose what I purpose, according to the flesh, that there may be with me, yes yes, and no, no?

2 Corinthians 13:1-2

The third time am I coming to you. By the mouth of two or three witnesses, every matter shall be established.

Philippians 3:1

Finally, my brethren, rejoice in the Lord. To write the same things to you is to me indeed not burdensome; but for you it is safe.

Philippians 4:4

Rejoice in the Lord always; and again I say, Rejoice.

Revelation 22:18-19

I testify to every one that hears the words of the prophecy of this book: if any one add to these things, God will add to him the plagues that are written in this book.

Treasury of Scripture Knowledge

Summary

As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.

General references

Bible References

So

2 Corinthians 1:17
In forming this purpose, did I, therefore, behave with levity? or do I purpose what I purpose, according to the flesh, that there may be with me, yes yes, and no, no?
2 Corinthians 13:1
The third time am I coming to you. By the mouth of two or three witnesses, every matter shall be established.
Philippians 3:1
Finally, my brethren, rejoice in the Lord. To write the same things to you is to me indeed not burdensome; but for you it is safe.
Philippians 4:4
Rejoice in the Lord always; and again I say, Rejoice.

Than

Revelation 22:18
I testify to every one that hears the words of the prophecy of this book: if any one add to these things, God will add to him the plagues that are written in this book.

General references

1 Corinthians 3:11
For other foundation can no man lay than that which is laid, which, is Jesus Christ.