On one occasion the Blessed One was dwelling among the Sakyans where there was a town of the Sakyans named Devadaha. There the Blessed One addressed the bhikkhus thus:
“Bhikkhus, I do not say of all bhikkhus that they still have work to do with diligence in regard to the six bases for contact, sn.iv.125 nor do I say of all bhikkhus that they do not have work to do with diligence in regard to the six bases for contact.
“I do not say of those bhikkhus who are arahants, whose taints are destroyed, who have lived the holy life, done what had to be done, laid down the burden, reached their own goal, utterly destroyed the fetters of existence, and are completely liberated through final knowledge, that they still have work to do with diligence in regard to the six bases for contact. Why is that? They have done their work with diligence; they are incapable of being negligent.
“But I say of those bhikkhus who are trainees, who have not attained their mind’s ideal, who dwell aspiring for the unsurpassed security from bondage, that they still have work to do with diligence in regard to the six bases for contact. Why is that? There are, bhikkhus, forms cognizable by the eye that are agreeable and those that are disagreeable. One should train so that these do not persist obsessing one’s mind even when they are repeatedly experienced. When the mind is not obsessed, tireless energy is aroused, unmuddled mindfulness is set up, the body becomes tranquil and untroubled, the mind becomes concentrated and one-pointed. Seeing this fruit of diligence, bhikkhus, I say that those bhikkhus still have work to do with diligence in regard to the six bases for contact.
“There are, bhikkhus, sounds cognizable by the ear … mental phenomena cognizable by the mind that are agreeable and those that are disagreeable. One should train so that these do not persist obsessing one’s mind even when they are repeatedly experienced. When the mind is not obsessed, tireless energy is aroused, unmuddled mindfulness is set up, the body becomes tranquil and untroubled, the mind becomes concentrated and one-pointed. Seeing this fruit of diligence, bhikkhus, I say that those bhikkhus still have work to do with diligence in regard to the six bases for contact.” sn.iv.126