Afraid of dying
The Buddha was asked whether everyone fears death and said no, and then said exactly who does and why: those attached to pleasures, those attached to the body, those who have done harm, and those in doubt about the path. That makes the fear something to look at rather than something to be ashamed of. The suttas prescribe recollecting mortality in calm so that it is familiar in fear, and they offer the mountain simile to a king — what is worth doing when death is certain. They do not promise fearlessness on a schedule, and they never use impermanence as a way to say the fear is silly. If a diagnosis is in the picture, ask your doctors what it means and what is ahead, as often as you need to; a palliative care team, a counsellor or a chaplain can help with the fear itself. The passages sit beside them, not in front of them.
What the suttas say
Mendicants, a woman or a man, a layperson or a renunciate should often review these five subjects. What five? ‘I am liable to grow old, I am not exempt from old age.’ A woman or a man, a layperson or a renunciate should often review this. ‘I am liable to get sick, I am not exempt from sickness.’ … ‘I am liable to die, I am not exempt from death.’ … ‘I must be parted and separated from all I hold dear and beloved.’ … ‘I am the owner of my deeds and heir to my deeds. Deeds are my womb, my relative, and my refuge. I shall be the heir of whatever deeds I do, whether good or bad.’ A woman or a man, a layperson or a renunciate should often review this.
The reflection the Buddha asked everyone, monastic or lay, to make often.
Where this stops: Never preached at someone frightened or grieving; owning one's deeds is never a reason to call an illness or a loss someone's kamma.
AN 5.57:1.1–1.9 · Subjects for Regular Reviewing
Pañcimāni, bhikkhave, ṭhānāni abhiṇhaṁ paccavekkhitabbāni itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā. Katamāni pañca? ‘Jarādhammomhi, jaraṁ anatīto’ti abhiṇhaṁ paccavekkhitabbaṁ itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā. ‘Byādhidhammomhi, byādhiṁ anatīto’ti abhiṇhaṁ paccavekkhitabbaṁ itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā. ‘Maraṇadhammomhi, maraṇaṁ anatīto’ti abhiṇhaṁ paccavekkhitabbaṁ itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā. ‘Sabbehi me piyehi manāpehi nānābhāvo vinābhāvo’ti abhiṇhaṁ paccavekkhitabbaṁ itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā. ‘Kammassakomhi, kammadāyādo kammayoni kammabandhu kammapaṭisaraṇo. Yaṁ kammaṁ karissāmi—kalyāṇaṁ vā pāpakaṁ vā— tassa dāyādo bhavissāmī’ti abhiṇhaṁ paccavekkhitabbaṁ itthiyā vā purisena vā gahaṭṭhena vā pabbajitena vā.
For this body is ailing, swaddled in its shell. If anyone dragging around this body claimed to be healthy even for an hour, what is that but foolishness? So you should train like this: ‘Though my body is ailing, my mind will be healthy.’ That’s how you should train.
Nakulapitā, old and ill — the training the Buddha gives him.
SN 22.1:3.2–3.6 · Nakula’s Father
Āturo hāyaṁ, gahapati, kāyo aṇḍabhūto pariyonaddho. Yo hi, gahapati, imaṁ kāyaṁ pariharanto muhuttampi ārogyaṁ paṭijāneyya, kimaññatra bālyā? Tasmātiha te, gahapati, evaṁ sikkhitabbaṁ: ‘āturakāyassa me sato cittaṁ anāturaṁ bhavissatī’ti. Evañhi te, gahapati, sikkhitabbanti.
But some of those liable to death are not frightened and terrified of death. Who are those frightened of death? It’s someone who isn’t free of greed, desire, fondness, thirst, passion, and craving for sensual pleasures.
Four reasons people fear death — craving for pleasures, for the body, having done harm, and doubt — which makes fear legible rather than shameful.
Where this stops: This is an analysis, not a reassurance; the fourth cause (doubt about the teaching) should not be used to pressure belief.
AN 4.184:2.4–3.2 · Fearless
atthi pana, brāhmaṇa, maraṇadhammo samāno na bhāyati, na santāsaṁ āpajjati maraṇassa. Katamo ca, brāhmaṇa, maraṇadhammo samāno bhāyati, santāsaṁ āpajjati maraṇassa? Idha, brāhmaṇa, ekacco kāmesu avītarāgo hoti avigatacchando avigatapemo avigatapipāso avigatapariḷāho avigatataṇho.
Suppose there were vast mountains of solid rock pressing against the sky drawing in from all sides and crushing the four quarters. So too old age and death advance upon all living creatures— aristocrats, brahmins, peasants, menials, corpse-workers, and scavengers. They spare nothing. They crush all beneath them.
King Pasenadi and the mountain simile — what is worth doing when death is certain.
Where this stops: Not to be preached at someone frightened or newly diagnosed.
SN 3.25:6.1–7.6 · The Simile of the Mountain
Yathāpi selā vipulā, nabhaṁ āhacca pabbatā; Samantānupariyāyeyyuṁ, nippothento catuddisā. Evaṁ jarā ca maccu ca, adhivattanti pāṇine; Khattiye brāhmaṇe vesse, sudde caṇḍālapukkuse; Na kiñci parivajjeti, sabbamevābhimaddati.
Now at that time the Buddha’s foot had been cut by a wooden splinter. The Buddha was stricken by harrowing pains; physical feelings that were painful, sharp, severe, acute, unpleasant, and disagreeable. But he endured unbothered, with mindfulness and situational awareness.
The Buddha in physical pain — the canon does not exempt him from the first arrow, and shows what enduring it looks like.
Where this stops: A description, not a standard to measure oneself against; bearing pain untroubled is the fruit of a long training, not an instruction to the person in pain today.
SN 1.38:1.3–1.5 · A Splinter
Tena kho pana samayena bhagavato pādo sakalikāya khato hoti. Bhusā sudaṁ bhagavato vedanā vattanti sārīrikā vedanā dukkhā tibbā kharā kaṭukā asātā amanāpā; tā sudaṁ bhagavā sato sampajāno adhivāseti avihaññamāno.