Suffer not thy mouth to cause thy flesh to sin; neither say thou before the angel, that it was an error: wherefore should God be angry at thy voice, and destroy the work of thine hands? Ecclesiastes 5:6 (KJV)
The commonplace advice is to control one’s mouth. But this reading is interesting because the consequence does not really follow the action, it rather reveals it. We do not commit sin because we vow, rather, its our vow which reveals our sinful nature. It is because we are sinners, we cannot commit to our vows – our actions will at some point of time dishonour the vows we commit to. All vows, in that sense are ill-made because it is doomed to be broken, because it’s a human who commits to it; a being that is naturally, by nature – characteristically flawed, because we are born sinners.