Answer : 3. "दशहरा पर्व "
Explanation :

1. The provision of worshipping the Khejri tree (Shami tree) is associated with the festival of Dussehra. On the day of Dussehra, worshipping the Shami tree destroys sins and leads to victory. On this day, worship is performed under the Shami tree and Shami leaves are taken as Prasad.

2. The Shami tree is considered a sacred tree in the Hindu religion. This tree is considered to be the abode of Shani Dev. Shani Dev is considered the god of justice. Therefore, by worshipping the Shami tree, one gets the blessings of Shani Dev and brings happiness, peace and prosperity in life.