SN 36.4
PTS: S iv 206
CDB ii 1262
Patala Sutta: The Bottomless Pit
translated from the Pali by
Nyanaponika Thera
Alternate translation: Thanissaro

"When, O monks, an untaught worldling says that in the great ocean there is a (bottomless) pit,[1] he speaks about something unreal and not factual.[2] 'The (bottomless) pit,' O monks, is rather a name for painful bodily feelings. When an untaught worldling is afflicted by painful bodily feelings, he worries and grieves, he laments, beats his breast, weeps and is distraught. He is then said to be an untaught worldling who cannot withstand the bottomless pit and cannot gain a foothold in it. But when a well-taught noble disciple[3] is afflicted by painful bodily feelings, he will not worry nor grieve and lament, he will not beat his breast and weep, nor will he be distraught. He is then said to be a noble disciple who can withstand the bottomless pit and has gained a foothold in it."

Who cannot bear the painful body-feelings that arise endangering his life, he trembles when afflicted. He wails and cries aloud, a weak and feeble man. He cannot stand against the pit, nor can a foothold he secure. But one who bears the painful body-feelings that arise, not trembling when his very life is threatened, he truly can withstand that pit and gain a foothold in its depth.

Notes

1.
Patala.
2.
Comy. (paraphrased): According to popular belief, there is in the ocean a very deep abyss hollowed out by the force of the water, which is the abode of aquatic animals as well as dragon deities (naga), etc. Hence, for these beings, this abyss provides a basis for their existence, a comfortable abode. Therefore, to call it a bottomless pit is unrealistic and not factual, because it gives an inadequate and non-evident meaning to the word. It is rather bodily pain, inseparable from bodily existence, which deserves to be called a "bottomless pit" of suffering, being a part of unfathomable Samsara.
3.
Comy.: In this Discourse, by the words "noble disciple," it is, in the first place, a stream-winner (sotapanna) that is meant. But also a meditator with strong insight and keen intellect is capable of withstanding feelings that arise without being carried away by them. He, too, ought to be included here (because he penetrates the feelings to some extent; Sub-comy.).