Ekadashi of Krishna Paksha of Ashwin month is called Indira Ekadashi. The Ekadashi which improves the condition of the wandering ancestors is called Indira Ekadashi.
Shaligram is worshiped on this day. Tulsi Dal must be offered on Shaligram ji on this day.
The end of the fast of Ekadashi is called Parana. Parana is done after sunrise on the next day of Ekadashi fast. It is very important to break the Ekadashi fast before the end of the Dwadashi date. If the Dwadashi tithi is over before sunrise, then Ekadashi fasting ends only after sunrise and doing so is tantamount to sin.
Sometimes Ekadashi fast is observed for two consecutive days. When Ekadashi fasting is for two days, then smart family members should observe Ekadashi fast on the first day. The second day of the Ekadashi is called the 'Dooji Ekadashi'. Sannyasis, widows and devotees wishing to attain salvation should observe a fast on Duji Ekadashi. Whenever Ekadashi fast is for two days, then Duji Ekadashi and Vaishnava Ekadashi fall on the same day.
It is said in the Puranas that there was a king named Indrasen in the golden age. One day Naradji came to him and started saying - O king! I am coming from Yamlok. There your father is very sad. For their salvation, you should fast on the Ekadashi of Krishna Paksha in the month of Ashwin. With the effect of this fast, your father will get salvation.
Indrasen fasted on Ashwin Krishna Ekadashi at the behest of Nardarji. Due to this his father got freed from the torture of Yamlok and went to heaven. Seeing the sight of the king, many people also started observing this fast.