Saṃyukta Āgama 291, Part 1

At that time, the World-Honored One addressed the monks, saying, "I teach the internal contact dharmas. Have you understood them?" Then a certain monk rose from his seat, adjusted his robe, bowed at the Buddha's feet with his head, joined his palms, and said to the Buddha, "The internal contact dharmas taught by the World-Honored One, I have understood them." At that time, that monk in front of the Buddha thus and thus recounted his own understanding, thus and thus the World-Honored One was displeased. Then the Venerable Ananda, standing behind the Buddha, was fanning the Buddha with a fan. The Buddha told Ananda, "According to the noble and sacred dhamma and vinaya, the internal contact dharmas are different from what this monk said." Ananda said to the Buddha, "Now is the time. I beseech the World-Honored One to explain the internal contact dharmas of the noble and sacred dhamma and vinaya to the monks. The monks, having heard, will accept and practice accordingly."

Explanation: The World-Honored One told the monks, "The internal contact dharmas I teach, do you all think you can grasp them?" At that time, a monk from outside rose from his seat, adjusted his robe, bowed at the Buddha's feet, joined his palms, and said to the Buddha, "The internal contact dharmas taught by the World-Honored One, I have grasped them." Then this monk in front of the Buddha recounted various sayings to verify himself, but whatever he said, the World-Honored One was displeased. Then the Venerable Ananda, holding a fan behind the Buddha, was fanning the Buddha. The Buddha told Ananda, "According to our noble and sacred dhamma and vinaya, the internal contact dharmas are different from what this monk said." Ananda said to the Buddha, "Now is a good time to explain. I beseech you, World-Honored One, to teach the monks the internal contact dharmas of the noble and sacred dhamma and vinaya. The monks, having heard, should accept and practice accordingly."

What is the internal contact dharmas? It is the contact within the supreme faculties: eye contacts form, ear contacts sound, nose contacts smell, tongue contacts taste, body contacts tangible objects, mind contacts dharmas. After contact, consciousness arises, and consciousness again contacts objects.