Patanjali's yoga sutras

हृदये चित्तसंवित् ॥ ३.३३ ॥

hṛdaye cittasaṃvit || 3.33 ||

hṛdaye = in the heart

citta = of the mind

saṃvit = the knowledge

By meditating on your heart chakra, you gain knowledge of your mind.