佛祖統紀 32.31

32.31

閻羅王昔為毘沙國王。與維陀始生王戰兵力不敵。因立誓願為地獄主。臣佐十八人領百萬眾。同立誓曰。後當奉助治此罪人。毘沙王者今閻羅王是。十八臣者今諸小王是。百萬眾者諸阿旁是（問地獄經阿旁此云無間）琰摩羅此言雙王。兄主男獄。妹主女獄（正法念經）兄妹皆作獄主。故云雙王。又苦樂並受故（經音義）。

In the past, King Yama was the king of Vaiśālī. He engaged in battle against King Vedasi-saṃbhava, but his military forces were no match. He then made a vow wishing to become the lord of the hells. His eighteen ministers and generals led a million troops, and together they made a vow, saying: 'In the future we will assist in punishing these sinners.' The king of Vaiśālī is the present King Yama; the eighteen ministers are the present minor kings; the million troops are the various ox-head wardens (*apāṅga*; the *Sūtra on Inquiring into Hells* says that *apāṅga* translates here as 'uninterrupted'). *Yamalarāja* here translates as 'Twin Kings': the elder brother rules the male hells, and the younger sister rules the female hells (*Saddharmasmṛtyupasthāna Sūtra*). Because brother and sister both serve as hell rulers, they are called 'Twin Kings'; moreover, it is because they endure both suffering and pleasure (*Pronunciation and Meaning of the Scriptures*).