Mula-Mantra, svarupa and the Essence of all the Vedas...

The Mantra is ॐ नमो नारायणाय (OM namo nArAyaNAya) and the quote under number 147 on the screenshot is from "Shree Narada-Purana". 

Cited from 

"Religion and Philosophy of Nalayira Divya Prabandham 

with special reference to NammAlvar" 

by Dr.N.Subbu Reddiar - #LINK TO PDF-SCAN