1… "Venerable sir, what is the cause and reason why it sometimes becomes warm?"

"There are, bhikkhu, what are called warm-cloud devas. When it occurs to them, ‘Let us revel in our own kind of delight,’ then, in accordance with their wish, it becomes warm. This, bhikkhu, is the cause and reason why it sometimes becomes warm."

1Sāvatthinidānaṁ. Ekamantaṁ nisinno kho so bhikkhu bhagavantaṁ etadavoca: "ko nu kho, bhante, hetu, ko paccayo, yenekadā uṇhaṁ hotī"ti?

"Santi, bhikkhu, uṇhavalāhakā nāma devā. Tesaṁ yadā evaṁ hoti: ‘yannūna mayaṁ sakāya ratiyā vaseyyāmā’ti, tesaṁ taṁ cetopaṇidhimanvāya uṇhaṁ hoti. Ayaṁ kho, bhikkhu, hetu, ayaṁ paccayo, yenekadā uṇhaṁ hotī"ti.

Catupaññāsamaṁ.