2 Thessalonians 2:15

Therefore, brethren, stand fast, and firmly hold the injunctions delivered to you, as ye have been taught, whether by our discourse, or by letter.

1 Corinthians 11:2

Now I praise you, brethren, that ye remember me in all things, and hold fast the injunctions as I delivered them unto you.

1 Corinthians 16:13

Watch ye, stand fast in the faith, be manful, be strong.

2 Thessalonians 2:2

that ye be not hastily agitated with apprehension, nor troubled, neither by spirit, nor by discourse, nor by letter, as coming from us, as though the day of the Lord was instantly approaching.

2 Thessalonians 3:6

Now we command you, brethren, in the name of our Lord Jesus Christ, to withdraw yourselves from every brother who walketh disorderly, and not according to the injunction which he hath received from us.

Romans 16:17

Now I beseech you, brethren, keep a sharp eye over those who cause divisions and offences contrary to the doctrine ye have learned, and turn away from them.

1 Corinthians 15:58

Wherefore, my beloved brethren, be stedfast, unmoveable, always abounding in the work of the Lord, knowing that your labour is not in vain in the Lord.

Philippians 4:1

WHEREFORE, my brethren, beloved, and very dear to me, my joy and crown, so stand fast in the Lord, O beloved.

2 Thessalonians 3:14

And if any man obey not our word by letter, mark that man, and maintain no society with him, that he may be ashamed.

Jude 1:3

Beloved, when I gave all diligence to write unto you concerning the common salvation, I held it necessary to write unto you, exhorting you to contend earnestly for the faith once delivered unto the saints.

Treasury of Scripture Knowledge

Summary

Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.

Bible References

Whether

2 Thessalonians 2:2
that ye be not hastily agitated with apprehension, nor troubled, neither by spirit, nor by discourse, nor by letter, as coming from us, as though the day of the Lord was instantly approaching.
2 Thessalonians 3:14
And if any man obey not our word by letter, mark that man, and maintain no society with him, that he may be ashamed.