Khaṇa: The Opportune Moment
Khaṇa is the narrow opening in which practice becomes possible. A whole generation died in the wilderness with the door standing open, and David, centuries downstream, still says "today," as though that same open hour had been handed forward intact. Whoever lets such an hour go by grieves later, so "today" comes as a summons and not as a reassurance that the offer will keep.
Dhammassavana: Hearing the Teaching
Dhammassavana is receiving the teaching from another's mouth, one of the conditions that open the path. Sound reaches the ear on its own, so the "if" in "if you will hear his voice" points past the ear to the place where a person decides things. Those at Meribah stood close enough to hear that voice plainly and drew nothing out of it, which is the whole risk of listening.
Thambha: Rigidity of Heart
Thambha is the stiffness of a mind that has stopped being teachable. Hardening is something people do with their own hands, and the caution goes to a crowd, since a whole camp can set at once around a shared grievance. A heart sets like clay left in the sun, holding whatever shape it had on the day it dried, and forty years of wandering did nothing to loosen it.
Kammaññatā: A Workable Mind
Kammaññatā is the pliancy that makes a mind usable. Gold goes into the fire so the smith can bend it, and a warm heart bends the same way, taking the shape of the voice it hears. Familiar words are the easiest to sit through unchanged, and an old line quoted once more through David moves only a mind still soft enough to be moved.
Appamāda: Heedfulness
Appamāda is watchful care, the last instruction the Buddha gave. "Today" carries that entire weight: the work belongs to this day, since no one is owed the next. Centuries stand between the wilderness and David, and more between David and whoever hears him now, which is how long a person can go on meaning to begin.