In India, the festival of Bhai Duj is celebrated on the third day of Diwali. The festival of Bhai Dooj is celebrated on the second day of Kartik month. This is the last day of 5 days long Diwali festival.
God of Death Yama and His Sister Yamuna's father is Lord Son. Yamuna loved Yamraj very much. She pleaded with them to come and have a meal at her house. Yamraj, busy with his work, could not go to his sister's house. On the day of Kartik Shukla, Yamuna again invited Yamraj for food once again.
Yamraj thought "I am the god of death nobody wants to call me home”. It is also my duty to follow the goodwill with which my sister is calling me. While leaving to the sister's house, Yamraj freed the souls suffering in hell.
Seeing Yamraj coming to his house, Yamuna was very happy. He worshiped and served many dishes and made food. Pleased with the hospitality offered by Yamuna, Yamraj asked Yamuna to ask for a boon. Yamuna said - "Brother! You come to my home every day and have a meal. On this day, like me, any sister should feed their brother with meal and give him a coconut, never let him fear you. "Yamraj gave such a boon and returned to Yamlok, giving the priceless gift to Yamuna.
It is believed that on this day, when brother come to their sisters home, they get wealth, age, and infinite happiness, they never fear premature death in life.
On the day of Bhai-Dooj, the sisters wish their brother for a long and healthy life and do Tilak with roli-sandalwood on their forehead. Then feed the brother sweets. This festival is symbol of brother-sisters strong relationship.