“He who guards his mouth from speech guards his heart from the passions.” – St Isaac the Syrian, Ascetical Homilies
The statement above is ‘very Biblical’ especially in light of this verse:
“For we all stumble in many ways. If anyone does not stumble in what he says, he is a perfect man, able to bridle the whole body as well.” (James 3:2)
*’not stumble in what he says’ = ‘guard his mouth’ (to speak rightly only)
**’bridle the whole body’ = ‘guard his heart (even body) from passions’.
Definition: “passions” = ‘sinful or lustful desires & cravings’