MantraOnNet.com: Ekadashi Fast
Said the Divine Grand Father:
The king Mandhata managed to the undisputed lord of three worlds by practicing the Ekada’s fasts of yore. Hence one shall fast both on the eleventh days of the light and dark fortnights. The queen Gandhari fasted on the day of the tenth phase of the moon, and lost her hundred sons in consequence. Hence one shall not fast on the eleventh
day of the fortnight. Even in spite of the dictum that
the god Hari presides over the day when the moon
is both in her tenth, and eleventh, phases, one should
fast on the day of the twelfth phase of the moon,
and break it on the day following.
One shall fast on
the day marked even by a Kala of Ekdaashi, or on
the day when the moon is successively in her eleventh, twelfth, and thirteenth, phases. The king
Rukmangada used to keep vigils on the nights of
the two Ekadashi’s and hear the Puranas recited to
him by the holy sages, in consequence whereof he
was liberated from the trammels of life and ascended
to heaven after death.