The story is from the time when in ancient times King Prith ruled Puchi. There lived a Brahmin named Jaidev in the kingdom of Prith. The Brahmin had four sons. All four were married. The elder daughter-in-law wanted to fast on Ganesh Chauth, she asked permission from her mother-in-law for this, but the mother-in-law refused. Whenever the daughter-in-law expressed her wish to her mother-in-law, the mother-in-law rejected it.
She started feeling worried and started narrating her pain to Lord Ganesha in her mind.
The elder daughter-in-law had a son eligible for marriage. Lord Ganesha became displeased and stole it. There was sadness in the house. The elder daughter-in-law prayed to her mother-in-law - "Mother, if you allow me, I will fast on Ganesh Chauth. Maybe, she will be happy and will bless us and I will get my son."
The elders always have affection for their grandchildren, hence he gave permission. The daughter-in-law observed a fast for Lord Ganesha. Pleased with this, Ganeshji took the form of a thin Brahmin and came to Jaidev's house. Mother-in-law and daughter-in-law served them food with great devotion and love.
Lord Ganesha had disguised himself as a Brahmin just to bless him, with his blessings the son of the elder daughter-in-law returned home.