When a friend is in trouble and you don't know how to help
The suttas' description of a friend worth having is concrete — one who gives and does what is hard for them, and stays with you when things go wrong — and their test for hard speech is whether it is true, beneficial, and timely, not whether it is comfortable. Love in the canon is directed toward the particular person before it is spread to everyone. Those passages can steady you for the conversation. They cannot tell you whether your friend is safe. If there is any sign of danger to their life, the call is to people who can act, and the suttas would not disagree.
What the suttas say
“Sir, good friends, companions, and associates are half the spiritual life.” Not so, Ānanda! Not so, Ānanda! Good friends, companions, and associates are the whole of the spiritual life. A mendicant with good friends, companions, and associates can expect to develop and cultivate the noble eightfold path.
Ānanda says half; the Buddha says all of it.
Where this stops: Never used to make someone without such friends feel that their practice is lacking.
SN 45.2:1.4–2.3 · Half the Spiritual Life
“upaḍḍhamidaṁ, bhante, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā”ti. Mā hevaṁ, ānanda, mā hevaṁ, ānanda. Sakalamevidaṁ, ānanda, brahmacariyaṁ, yadidaṁ—kalyāṇamittatā kalyāṇasahāyatā kalyāṇasampavaṅkatā. Kalyāṇamittassetaṁ, ānanda, bhikkhuno pāṭikaṅkhaṁ kalyāṇasahāyassa kalyāṇasampavaṅkassa—ariyaṁ aṭṭhaṅgikaṁ maggaṁ bhāvessati, ariyaṁ aṭṭhaṅgikaṁ maggaṁ bahulīkarissati.
Even as a mother would protect with her life her child, her only child, so too for all creatures unfold a boundless heart. With love for the whole world, unfold a boundless heart: above, below, all round, unconstricted, without enmity or foe. When standing, walking, sitting, or lying down while yet unweary, keep this ever in mind; for this, they say, is a divine meditation in this life.
The Metta Sutta's central image, in the canon's own words.
Where this stops: The verses are an ideal of the practitioner; the opening lines describing a skilled and honest person are a description, not a prerequisite for beginning. Never use it to quiet anger that has something to say, and never present it as a recitation that protects anyone. The mother guarding her only child is not for someone after a pregnancy loss.
Kp 9:7.1–9.4 · The Discourse on Love
Mātā yathā niyaṁ puttam Āyusā ekaputtamanurakkhe; Evampi sabbabhūtesu, Mānasaṁ bhāvaye aparimāṇaṁ. Mettañca sabbalokasmi, Mānasaṁ bhāvaye aparimāṇaṁ; Uddhaṁ adho ca tiriyañca, Asambādhaṁ averamasapattaṁ. Tiṭṭhaṁ caraṁ nisinno va, Sayāno yāvatāssa vitamiddho; Etaṁ satiṁ adhiṭṭheyya, Brahmametaṁ vihāramidhamāhu.
“In the same way, prince, the Realized One does not utter speech that he knows to be untrue, false, and pointless, and which is disliked by others. The Realized One does not utter speech that he knows to be true and correct, but which is harmful and disliked by others. The Realized One knows the right time to speak so as to explain what he knows to be true, correct, and beneficial, but which is disliked by others. The Realized One does not utter speech that he knows to be untrue, false, and pointless, but which is liked by others. The Realized One does not utter speech that he knows to be true and correct, but which is harmful, even if it is liked by others. The Realized One knows the right time to speak so as to explain what he knows to be true, correct, and beneficial, and which is liked by others. Why is that? Because the Realized One has sympathy for sentient beings.”
Prince Abhaya — the test for whether and when to say a hard thing.
Where this stops: For deciding whether and when to say one particular hard thing; it does not judge a relationship as a whole, and it is not a reason to say nothing. Nor does it mean anyone owes another person news about their own body, health or pregnancy, or should speak when speaking would put them at risk.
MN 58:8.1–8.8 · With Prince Abhaya
“Evameva kho, rājakumāra, yaṁ tathāgato vācaṁ jānāti abhūtaṁ atacchaṁ anatthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, na taṁ tathāgato vācaṁ bhāsati. Yampi tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ anatthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, tampi tathāgato vācaṁ na bhāsati. Yañca kho tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ atthasaṁhitaṁ sā ca paresaṁ appiyā amanāpā, tatra kālaññū tathāgato hoti tassā vācāya veyyākaraṇāya. Yaṁ tathāgato vācaṁ jānāti abhūtaṁ atacchaṁ anatthasaṁhitaṁ sā ca paresaṁ piyā manāpā, na taṁ tathāgato vācaṁ bhāsati. Yampi tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ anatthasaṁhitaṁ sā ca paresaṁ piyā manāpā tampi tathāgato vācaṁ na bhāsati. Yañca tathāgato vācaṁ jānāti bhūtaṁ tacchaṁ atthasaṁhitaṁ sā ca paresaṁ piyā manāpā, tatra kālaññū tathāgato hoti tassā vācāya veyyākaraṇāya. Taṁ kissa hetu? Atthi, rājakumāra, tathāgatassa sattesu anukampā”ti.
Mendicants, you should associate with a friend who has seven factors. What seven? They give what is hard to give. They do what is hard to do. They endure what is hard to endure. They reveal their secrets to you. They keep your secrets. They don’t abandon you in times of trouble. They don’t look down on you in times of loss. You should associate with a friend who has these seven factors. A friend gives what is hard to give, and does what’s hard to do. They put up with your harsh words, and with things hard to endure. They tell you their secrets, and keep your secrets for you. They don’t abandon you in times of trouble, or look down on you in times of loss.
What to look for and what to be in a friend.
AN 7.36:1.1–3.4 · A Friend (1st)
Sattahi, bhikkhave, aṅgehi samannāgato mitto sevitabbo. Katamehi sattahi? Duddadaṁ dadāti, dukkaraṁ karoti, dukkhamaṁ khamati, guyhamassa āvi karoti, guyhamassa pariguhati, āpadāsu na jahati, khīṇena nātimaññati. Imehi kho, bhikkhave, sattahi aṅgehi samannāgato mitto sevitabboti. Duddadaṁ dadāti mitto, dukkarañcāpi kubbati; Athopissa duruttāni, khamati dukkhamāni ca. Guyhañca tassa akkhāti, guyhassa parigūhati; Āpadāsu na jahāti, khīṇena nātimaññati.
We will meditate spreading a heart of love to that individual. And with them as a basis, we will meditate spreading a heart full of love to everyone in the world—abundant, expansive, limitless, free of enmity and ill will.’
Mettā starts with the specific person who spoke harshly, then widens; the order matters.
Where this stops: A training for one's own mind under hard speech. It is never a reason to stay where someone keeps speaking to you with contempt or threats, and never a ruling on whether to leave.
MN 21:11.14 · The Simile of the Saw
Tañca puggalaṁ mettāsahagatena cetasā pharitvā viharissāma, tadārammaṇañca sabbāvantaṁ lokaṁ mettāsahagatena cittena vipulena mahaggatena appamāṇena averena abyābajjhena pharitvā viharissāmā’ti.