"On the occasion of Chhat, the festival of 'Surya upasna' (prayers to the Sun), I extend best wishes to all countrymen. May the 'Chhat mata' (mother Chhat) bring peace and prosperity in everybody's life," he tweeted.
The age-old tradition, in which the Sun God is prayed, is celebrated mainly by people from Bihar and eastern Uttar Pradesh.
The puja starts with the ritual of 'Nahai-Khai', in which devotees prepare traditional food after bathing.
On the third day those observing Chhath puja stand in water and offer 'arghya' to the setting sun amid chanting of mantras and hymns.
And on the final day of the puja, devotees and their friends and relatives assemble at the river bank before sunrise and offer 'arghya' to the rising sun.