'Sound Doctrine' in the Bible

Holding fast the faithful word as he hath been taught, that he may be able by sound doctrine both to exhort and to convince the gainsayers.

But speak thou the things which become sound doctrine:

but what is agreeable to sound doctrine: advise the aged to be prudent, grave, temperate, sound in faith,

in all things shewing thyself a pattern of good works, with uncorruptness in teaching, gravity, sound doctrine that cannot be condemned;