Mbh 7.202.4d

The illustrious God of gods, therefore, is called Vrishakapi. And since Maheswara by means of his two eyes closed (in meditation), created through sheer force of will a third eye on his forehead, he is for that reason called the Three-eyed. Whatever of unsoundness there is in the bodies of living creatures, and whatever of soundness there is in them, represent that God. He is the wind, the vital airs called Prana, Apana (and the others) in the bodies of all creatures, including even those that are diseased. He who adoreth any image of the Phallic emblem of that high-souled God, always obtaineth great prosperity by that act. Downwards fiery, and half the body, that is auspiciousness is the moon. His auspiciousness is the moon. So also half his soul is fire and half the moon. His auspicious form, full of energy, is more blazing than the forms of the gods. Among men, his blazing and terrible form is called fire. With that auspicious form he practiseth Brahmacharya. With that other terrible form he as supreme Lord devoureth everything. And since he burneth, since he is fierce, since he is endued with great prowess, and since he devoureth flesh and blood and marrow, he is for this called Rudra. Even such is the deity called Mahadeva, armed with Pinaka, who, O Partha, was seen by thee engaged in slaying thy foes in advance of thy car. After thou hadst vowed to slay the ruler of the Sindhus, O sinless one, Krishna showed thee this God, in thy dream, sitting on the top of that foremost of mountains. This illustrious God proceedeth in advance of thee in battle. It is he who gave thee those weapons with which thou didst slay the Danavas. The hymn approved of the Vedas, and called Sata-Rudriya, in honour of that God of gods, that excellent, famous, life-enhancing, and sacred hymn, has now, O Partha, been explained to thee.