The Upanishads, Part 2 (SBE15), by Max Müller, [1879], at sacred-texts.com
This is indeed the highest penance, if a man, laid up with sickness, suffers pain 1. He who knows this, conquers the highest world.
This is indeed the highest penance, if they carry a dead person into the forest 2. He who knows this, conquers the highest world.
This is indeed the highest penance, if they place a dead person on the fire 3. He who knows this, conquers the highest world.
194:1 The meaning is that, while he is suffering pain from illness, he should think that he was performing penance. If he does that, he obtains the same reward for his sickness which he would have obtained for similar pain inflicted on himself for the sake of performing penance.
194:2 This is like the penance of leaving the village and living in the forest.
194:3 This is like the penance of entering into the fire.