Bg 16.21

tri-vidhaṁ narakasyedaṁ
dvāraṁ nāśanam ātmanaḥ
kāmaḥ krodhas tathā lobhas
tasmād etat trayaṁ tyajet
Synonyms: 
tri-vidham — of three kinds; narakasya — of hell; idam — this; dvāram — gate; nāśanam — destructive; ātmanaḥ — of the self; kāmaḥ — lust; krodhaḥ — anger; tathā — as well as; lobhaḥ — greed; tasmāt — therefore; etat — these; trayam — three; tyajet — one must give up.
Translation: 
There are three gates leading to this hell – lust, anger and greed. Every sane man should give these up, for they lead to the degradation of the soul.
Purport: 

The beginning of demoniac life is described herein. One tries to satisfy his lust, and when he cannot, anger and greed arise. A sane man who does not want to glide down to the species of demoniac life must try to give up these three enemies, which can kill the self to such an extent that there will be no possibility of liberation from this material entanglement.