yah parva sanpurn bihar aur uÿar pradesh ke purvi kshetron men bari shraddha se manaya jata hai jismen santan evan sukh-samriddhi ki prapti ke lie bhagvan surya dev ki aradhna ki jati hai. yah parva bahut hi saf-safai aur nishtha ke sath manaya jata hai. chath vrat dipavli ke chah din bad ‘kharna’ se aranbh hota hai. kharna ke din vrati snan-dhyan kar sham ko chandrama ko gur ki khir evan roti ka bhog lagate hain.
kharna ke bad dusre din 24 ghante ka upvas aranbh hota hai. agle din sham ko nadi athva talab men khare hokar vratigan dubte surya ko aghrya dete hain. fir agli subah ko isi prakar ugte surya ko aghrya adi dekar mantra jap athva unki stuti, arti adi karte hain. tatpashchat prasad bantakar svayan bhi grahan karte hain.
katha hai ki svayan manu ke putra raja priyavrat ko adhik samay bit jane ke bad bhi jab koi santan nahin hui to maharshi kashyap ne putreshti yagya karakar unki patni ko prasad diya. prasad khane se garbh to thahar gaya, kintu bad men rani ne mrit putra ko janm diya jise dekhakar ve tatkshan muchrchit ho gain. priyavrat mrit shishu ko lekar shmashan gae aur putra viyog men unhonne bhi pran tyagne ka nishchay kiya.
usi samay shashthi devi vahan prakat huin. mrit balak ko bhumi par rakhakar raja ne devi ko pranam kiya. devi ne raja ko shashthi vrat karne ki salah di aur balak ko jivit kar diya. raja ne usi din ghar jakar niyamanusar shashthi devi ki puja ki. tabhi se yah vrat prasiddh ho gaya.