Arjuna observed penance to obtain the Pasupatastra from Lord Siva. Pleased with his penance, Lord Siva wanted to reward him with the weapon, said V.S. Karunakarachariar in a discourse. But Goddess Parvati laid down a condition. She said that Arjuna had never turned away from a battle. So She said that Siva should draw Arjuna into a fight, so that he would turn away and She would be witness to this.
In the meanwhile, Duryodhana had sought the help of a demon to disturb Arjuna’s penance. This demon took the form of a porcupine and went to attack Arjuna. Siva and Parvati, in the guise of a hunter and his wife, arrived just as this attack began. Arjuna, although immersed in penance, had the intuitive sense of a born fighter and could sense that an attack against him was about to happen. So even while not giving up his penance, he pulled out an arrow to strike the porcupine. But Lord Siva also took aim and killed the porcupine.
This angered Arjuna, who questioned the hunter (Siva). Siva replied that as he was a hunter, and so hunting down animals constituted his livelihood. A quarrel then broke out between Arjuna and Siva, which ended in a fight. As they fought, Parvati waited for Arjuna to turn back from the fight and run. But as time passed, She was worried that Siva, instead of staging a mock battle, might get serious and cause Arjuna some harm. So She recited a mantra, which said that Siva’s bow and arrow and their target were all auspicious.
As Tripurantaka, Siva had wielded a bow and arrow and burnt down the forts of three demons.
This mantra chanted by Parvati may also be interpreted as a reference to Lord Narayana’s manifestation as Rama, and His arrows.
It may also be taken to be a reference to Agni. This mantra wards off death.
