The Kathopanishad Verse 1.3.3 – आत्मानँ रथितं विद्धि शरीरँ रथमेव तु

आत्मानँ रथितं विद्धि शरीरँ रथमेव तु ।
बुद्धिं तु सारथिं विद्धि मनः प्रग्रहमेव च ॥ ३ ॥

atmanam rathitaṃ viddhi sariram rathameva tu |
buddhiṃ tu sarathim viddhi manah pragrahameva ca || 3 ||

Know that the soul is the master and rider in the chariot. The body is the chariot. The intellect is the charioteer. The mind is the horse reigns.