Mbh 3.166.2d

O Pandava, my own weapon Raudra shall attend upon thee.’ Thereupon Mahadeva, well-pleased, granted to me the mighty weapon, Pasupata. And, having granted that eternal weapon, he also said unto me, This must never be hurled at mortals. If discharged at any person of small energy, it would consume the universe. Shouldst thou (at any time) be hard pressed, thou mayst discharge it. And when all thy weapons have been completely baffled, thou mayst hurl it.’ Then when he having the bull for his mark, had been thus gratified, there stood manifest by my side that celestial weapon, of resistless force capable of baffling all weapons and destructive of foes and the hewer of hostile forces and unrivalled and difficult to be borne even by the celestials, the demons and the Rakshasas. Then at the command of that god, I sat me down there. And in my very sight the god vanished from the spot.’”