法苑珠林 4.58

4.58

又起世經。問言。復有何因緣。於冬分時夜長晝短。佛答比丘。日天宮殿過六月已漸向南行。每於一日移六拘盧奢。無有差失。當於是時日天宮殿在閻浮洲最極南垂。地形狹小日過速疾。以此因緣。於冬分時晝短夜長。復何因緣。於春夏時晝長夜短。佛答云。日天宮殿過六月已漸向北行。每一日中移六俱盧奢無有差失。異於常道。當於是時。在閻浮洲處中而行。地寬行久所以晝長。以此因緣。春夏晝長夜分短促。

The Lokotpatti-sūtra also asks: 'Furthermore, by what cause and condition are the nights long and the days short in the winter season?' The Buddha answered the monks: 'When the sun-deva's palace has passed six months, it gradually travels southward, shifting six krośas each day without any error. At this time, the sun-deva's palace is at the southernmost extremity of Jambudvīpa; the land's shape being narrow and small, the sun passes by rapidly. By this cause and condition, the days are short and the nights are long in the winter season. Furthermore, by what cause and condition are the days long and the nights short in the spring and summer?' The Buddha answered: 'When the sun-deva's palace has passed six months, it gradually travels northward, shifting six krośas each day without any error, diverging from its regular path. At this time, it travels through the middle of Jambudvīpa; the land being broad, its passage takes longer, and therefore the days are long. By this cause and condition, in spring and summer the days are long and the night divisions are brief.'