Saṃyuktāgama 146. [Discourse on the Three Feelings]
Thus have I heard. At one time the Buddha was staying at Sāvatthī in Jeta's Grove, Anāthapiṇḍika's Park.
At that time the Blessed One said to the monks: “The existence of what is the cause, by clinging to what, by being fettered and attached to what, by seeing what as the self, does one revolve in the three feelings in the world?”
The monks said to the Buddha: “The Blessed One is the root of the Dharma, the eye of the Dharma, the foundation of the Dharma …” to be recited fully in the same way in the sequence of the above three discourses.