There are 2 versions of story about Raksha Bandhan
1 st one is
Raksha Bandhan is not only for meant for siblings, but for protection for any loved one. 'Raksha' means protection and 'bandhan' means bond. Hence the festival does not signify bond between a brother and sister only.
Once Indra, the God of Heaven was about to go into battle and was feeling a little apprehensive. When his wife tied a sacred thread to his arm for his protection and assurance all his fears vanished and he was successful in all his endeavors. From then on began the tradition of celebrating Raksha Bandhan. A festival of protection for loved ones.
2nd one is
Raksha Bandhan In Mythology And History And What It Is Today
The roots of most of the Hindu festivals can be traced to Hindu Mythology. We do hear about why is Holi celebrated or what is the significance of Diwali but hardly anyone knows why Raksha Bandhan is celebrated. All one knows about it is that it is the festival for the brothers and the sisters when they wish good life to each other and the sister ties rakhi to her brother.
Raksha Bandhan is mentioned in our epics as a festival of Gods. It is said that Yamuna, the sister of Yama, the lord of Death used to tie rakhi to his brother on every Shravan Purnima. Indrani tied Rakhi to his brother Lord Indra. Yama was so impressed by the occasion that he declared that who ever got a Rakhi tied from his sister would become immortal. From that day onwards girls tie rakhi to their brothers wishing them a long life and brothers bestow their blessings by promising to take care of the sisters through thick and thin.
While tying the rakhi, the girls chant
"Yena baddho Balee raajaa daanavendro mahaabalah
tena twaam anubadhnaami rakshe maa chala maa chala"
meaning "I am tying a Rakhi on you, like the one on mighty demon king Bali. Be firm, O Rakhi, do not falter."
The legend relates that the mighty Demon king Raja Bali was a great devotee of Lord Vishnu. When lord Indra could not counter Bali, he went to Lord Vishnu for help. Vishnu overthrew Bali to the nether world. Lord Vishnu promised King Bali immortality till he would be crowned as Indra and also that he would guard the kingdom of Patala leaving his own abode in Vaikunth.
Godess Laxmi, the consort of Lord Vishnu, wished the Lord to be back at Vaikunth. Disguised as a Brahmin woman she went to Bali to seek refuge till her husband returned home after finishing some important task. King Bali obliged. With her came the happiness and wealth. All auspicious things happened.
On the Shravan Purnima Goddess tied the sacred thread to Bali and prayed for his well being. Bali was touched by the gesture. He accepted her as her sister and requested her to make a wish. At this She revealed herself and told that it war Narayan himself guarding hid Kindom. King Bali immediately requested the Lord to return to his abode.
From that day on, girls tie rakhi to their brothers and seek blessings.
Happy Raksha Bandhan