俱舍論頌疏論本 12.12

12.12

釋曰：剎那百二十為一怛剎那，六十怛剎那為一臘縛，三十臘縛為一牟呼栗多，三十牟呼栗多為一晝夜，三十晝夜為一月，十二月為一年。於一年中分為三際，謂寒、熱、雨，各有四月。十二月中六月減夜，以一年內夜總減六，云何如是？故有頌曰：「寒熱雨際中，一月半已度。於所餘半月，智者知夜減。」

The explanation says: One hundred and twenty kṣaṇas make one tatkṣaṇa; sixty tatkṣaṇas make one lava; thirty lavas make one muhūrta; thirty muhūrtas make one day-and-night; thirty days-and-nights make one month; twelve months make one year. A year is divided into three seasons, namely cold, heat, and rain, each having four months. Within the twelve months, six months have reduced nights, so that in a year there are six reduced nights in total. Why is it so? Thus a verse says:
'In the seasons of cold, heat, and rain,
When one and a half months have passed,
In the remaining half month,
The wise know the night is reduced.'