From the Commentary to the Brahmajla sutta ( translated by Bodhi)
These are the Cātumahārājika gods.97 One young god among
these, it is told, wishing to celebrate a festival, set out by chariot on the
roadway along with his retinue. Another of those gods, going out for a
walk, saw the first one riding ahead of him. He became angry and
exclaimed: “That miserable wretch! There he is going along puffed up
with rapture to the bursting point, as if he had never seen a festival
before.” The first, turning around and realizing that the other was
angry—angry people being easy to recognize—became angry in turn
and retorted: “What have you got to do with me, you hot-headed
fellow? My prosperity was gained entirely by my own meritorious
works. It has nothing to do with you!”
Now if one of these gods gets angry, but the other remains
unangered, the latter protects the former (from passing away). But if
both get angry, the anger of one will become the condition for the
anger of the other, and both will pass away with their harems weeping.
This is the natural law (dhammatā).
Sub.Cy. If one remains unangered, the anger of the other, not
getting any fuel, will arise for only one turn and then subside. It will
become extinguished like fire immersed in water, and cannot cause his
death. But if both get angry, the anger of each will grow stronger and
stronger, intensifying the anger of the other, and become fierce in its
attacks, capable of consuming the support (of the vital processes).
Then their anger will burn up the heart-base (hadayavatthu) and
destroy their extremely delicate material body. Subsequently, the
entire individual form will disappear.
“The natural law”: the purport is that their passing away from that
plane is due to the delicacy of their material bodies and the strength of
their arisen anger, as well as to the specific nature of their material and
immaterial dhammas.