Somvati Amavasya is the most auspicious Amavasya day to worship Lord Vishnu, Lord Shiva, and Pitru Devatas or dead ancestors.
Somavathi Amavasya, also known as Ama Somvar Vrata, was observed by King Yudhistira to get noble successors for his dynasty.
Sankalpa Mantra for Somvati Amavasya puja is the most auspicious prayer to chant which is dedicated to Lord Sri Narayana. The story of Somvati Amavasya (Vrat katha) is associated with a moneylender’s daughter and a washer woman.
Sankalpa Mantra to worship Lord Lakshmi Narayana on Somvati Amavasya – Ama Somvar Vrata Stotra:
parama soubhagya kama asyaam
brahma Vishnu shivatma kashwaththa vrukshe
yathamilithopacharie lakshmi narayana poojam karsihye”