Patanjali Yoga Sutra 2.8

Dvesha is that which trails after pain.

दुःखानुशयी द्वेषः ॥

duhkhanusayi dvesah ||

Dvesha is that which trails after pain.

When something hurts you, it leaves a mental "flinch." You instinctively avoid things, get angry, or build walls to protect yourself—even when you are completely safe now.