Bhagavad Gita, Chapter 16, Verse 21

Triple is this gate of hell, destructive of the self, lust, anger and greed; therefore one should forsake these three.

The chapter's whole warning is compressed here into three gates: lust, anger and greed.

Naming lust, anger, and greed gives Arjuna something concrete and memorable to watch for. After a long, detailed description, the warning is made simple.