Yato- yato niscarati manascancalam asthiram
Tatastato -niyamyai tad Atmanyeva vasam nayet
Prasantamanasm hyenam yoginam sukham uttamam
Upaiti santa-rajasam Brahma -bhutam akalmasam
Yunjannevam sada tmanam yogi vigata- kalmasah
Sukhena Brahma-samparsam atyantam sukham asnute
Sarvabhutastham Atmanam sarvabhutani catmani
Iksate yogayuktatma sarvatra samadarsanah
-Bhagavadgita, 6.26, 27, 28 & 29
The last line of the stanza : " Esa dharmah sanatanah ." (Manusmrti)
See Part Sixteen
The "panca -mahayajnas, " including vaisvadeva, are dealt with in earlier chapters.
GITA:
Dhyayato visayan pumsah sangastesu pajayate
Sangat samjayate kamah kamat krodho bhijayate
Krodhadbhavati sammohah sammohat smrti-vibhramah
Smrtibhramsad buddhinaso buddhinasat pranasyati
-Bhagavatgita, 2.62 & 63
For a general background, please see here