2 Thessalonians 2:15

be stedfast therefore, and firmly maintain the doctrine I have delivered to you, either by word of mouth, or by my letter.

1 Corinthians 11:2

now I commend you, brethren, for remembring all my orders, and for keeping the rules I delivered to you.

1 Corinthians 16:13

Be upon the watch, stand firm in the faith, behave your selves like men of fortitude:

2 Thessalonians 2:2

you would not by any pretended revelation, by any discourse or epistle ascrib'd to us, be immediately perplex'd in your minds, or under any concern for the approach of the day of the Lord.

2 Thessalonians 3:6

We direct you, brethren, in the name of our Lord Jesus Christ, to withdraw from all those of your brethren, whose conduct is irregular, and not agreeable to the instructions they received from us.

Romans 16:17

Now I beseech you, brethren, mark those who cause divisions and revolts against the doctrine which you have learned; and avoid them.

1 Corinthians 15:58

therefore, my beloved brethren, be ye inflexibly steady, and continually surpass others in the work of the Lord, knowing that he will not leave your christian labour unrewarded.

Philippians 4:1

Wherefore, my dearly beloved brethren, my joy and my crown, whom I long to see, continue firm in your christian profession, my beloved.

2 Thessalonians 3:14

and if any one should disregard what we have prescrib'd, signify it to us by letter, and don't converse with him, that he may be put to shame.

Jude 1:3

My beloved, as I was strongly bent upon writing to you of our common salvation, I thought it necessary to write to you at present, and exhort you to contend earnestly for the faith, which was once delivered to 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
you would not by any pretended revelation, by any discourse or epistle ascrib'd to us, be immediately perplex'd in your minds, or under any concern for the approach of the day of the Lord.
2 Thessalonians 3:14
and if any one should disregard what we have prescrib'd, signify it to us by letter, and don't converse with him, that he may be put to shame.