Matsyapurana 145.36

145.36

taiḥ śiṣṭaiścalito dharmaḥ sthāpyate vai yuge yuge
trayī vārttā daṇḍanītiḥ prajāvarṇāśramepsayā //

In this way, the two kinds of dharmas are called the Siṣṭâchâra The expression Siṣṭa is made of the root śviṣ and suffix kta Those who remained in the preceding Manvantara, Manu, the propagator of the race and the Saptaṛṣis are called the Siṣṭas The pious men during the Manvantaras and the Saptaṛṣis along with Manu are said to be the promoters of the universe These persons i e Siṣṭas establish dharma, which changes in Yuga after Yuga by giving out the Vedas, message livelihood, the criminal procedure code and Varṇâśramachâra. At the end of a Manvantara the Siṣṭa puruṣas establish the Vedikdharma by means of Varṇâśrama and authority Thus coming down from Siṣṭas to Siṣṭas This is the eternal Siṣṭâchara—34 37