Acts 20:31

Therefore watch, remembering that for three years, I ceased not to warn every one, night and day, with tears.

1 Thessalonians 5:14

Now we exhort you, brethren, warn the disorderly, comfort the feeble-minded, support the weak, be long suffering toward all men.

Treasury of Scripture Knowledge

Summary

And what cause soever shall come to you of your brethren that dwell in their cities, between blood and blood, between law and commandment, statutes and judgments, ye shall even warn them that they trespass not against the LORD, and so wrath come upon you, and upon your brethren: this do, and ye shall not trespass.

Bible References

Warn them

Acts 20:31
Therefore watch, remembering that for three years, I ceased not to warn every one, night and day, with tears.
1 Thessalonians 5:14
Now we exhort you, brethren, warn the disorderly, comfort the feeble-minded, support the weak, be long suffering toward all men.