The Buddha states plainly that an injured tongue or body produces an offensive odor, a physical manifestation of decay. He then equates this to the mind when it is similarly wounded, suggesting it too emits a foulness. This is not a literal smell, but a metaphorical one, representing the pervasive and unpleasant quality of suffering that arises from a mind afflicted by negative states.

In Buddhist thought, the "injury" to the mind refers to its entanglement with the three poisons: greed (lobha), hatred (dosa), and delusion (moha). These afflictions, often rooted in a mistaken sense of self or ego (atta), corrupt the mind's natural clarity and purity. When the mind is dominated by these poisons, it generates unwholesome karma, leading to further suffering in this life and future rebirths, much like a festering wound spreads infection. The "bad smell" signifies the repulsive nature of these mental states and their consequences, affecting not only oneself but also those around you.

In your life: Recognize that anger, resentment, or persistent worry are not just fleeting emotions, but "injuries" to your mental well-being. Practice mindfulness to observe these states without judgment, and actively cultivate wholesome states like compassion and equanimity to purify your mind.