This entry is going to be mostly quotes...one from scripture and one from Matthew Henry's commentary on Isaiah 2 (that one is pretty long but worth the read).
"Stop regarding man
in whose nostrils is breath,
for of what account is he?"
~ Isaiah 2:22 ~
Matthew Henry:
"To make those that have trusted in an arm of flesh ashamed of their confidence (v. 22): "Cease from man. The Providences of God concerning you shall speak this aloud to you, and therefore take warning beforehand, that you may prevent the uneasiness and shame of disappointment; and consider,
1. How weak man is: His breath is in his nostrils, puffed out every moment, soon gone for good and all.’’ Man is a dying creature, and may die quickly; our nostrils, in which our breath is, are of the outward parts of the body; what is there is like one standing at the door, ready to depart; nay the doors of the nostrils are always open, the breath in them may slip away ere we are aware, in a moment. Wherein then is man to be accounted of? Alas! no reckoning is to be made of him, for he is not what he seems to be, what he pretends to be, what we fancy him to be. Man is like vanity, nay, he is vanity, he is altogether vanity, he is less, he is lighter, than vanity, when weighed in the balance of the sanctuary. "
2. How wise therefore those are that cease from man;’’ it is our duty, it is our interest, to do so. "Put not your trust in man, nor make even the greatest and mightiest of men your confidence; cease to do so. Let not your eye be to the power of man, for it is finite and limited, derived and depending; it is not from him that your judgment proceeds. Let not him be your fear, let not him be your hope; but look up to the power of God, to which all the powers of men are subject and subordinate; dread his wrath, secure his favour, take him for your help, and let your hope be in the Lord your God.’’"
* Found on blueletterbible.org; Matthew Henry's Commentary on Isaiah 2