[28] "And how, Mahānāma, is a noble disciple one who guards the doors of the sense faculties (indriya)? Here, Mahānāma, a noble disciple, having seen a form (rūpa) with the eye, does not grasp at the sign (nimitta), does not grasp at the features (anubyañjana). Since, if he were to dwell with the eye faculty unrestrained, evil, unwholesome states of covetousness and grief (abhijjhā-domanassa) might flow in upon him, he practises for its restraint; he guards the eye faculty, he attains restraint with regard to the eye faculty. Having heard a sound with the ear … having smelt an odour with the nose … having tasted a flavour with the tongue … having touched a tangible with the body … having cognized a dhamma with the mind, he does not grasp at the sign, does not grasp at the features. Since, if he were to dwell with the mind faculty unrestrained, evil, unwholesome states of covetousness and grief might flow in upon him, he practises for its restraint; he guards the mind faculty, he attains restraint with regard to the mind faculty. Thus indeed, Mahānāma, is a noble disciple one who guards the doors of the sense faculties."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.