Mbh 3.38.4b

Clad in rags made of grass and furnished with a black deerskin and a stick, he commenced to eat withered leaves fallen upon the ground. And he passed the first month, by eating fruits at the interval of three nights; and the second by eating at the interval of the six nights; and the third by eating at the interval of a fortnight. When the fourth month came, that best of the Bharatas--the strong-armed son of Pandu--began to subsist on air alone. With arms upraised and leaning upon nothing and standing on the tips of his toes, he continued his austerities. And the illustrious hero’s locks, in consequence of frequent bathing took the hue of lightning or the lotus. Then all the great Rishis went together unto the god of the Pinaka for representing unto him about the fierce asceticism of Pritha’s son. And bowing unto that god of gods, they informed him of Arjuna’s austerities saying, ‘This son of pritha possessed of great energy is engaged in the most difficult of ascetic austerities on the breast of the Himavat. Heated with his asceticism, the earth is smoking all round, O god of gods. We do not know what his object is for which he is engaged in these austerities. He, however, is causing us pain. It behoveth thee to prevent him!’ Hearing these words of those munis with souls under perfect control, the lord of all creatures--the husband of Uma said, ‘It behoveth you not to indulge in any grief on account of Phalguna! Return ye all cheerfully and with alacrity to the places whence ye have come. I know the desire that is in Arjuna’s heart. His wish is not for heaven, nor for prosperity, nor for long life. And I will accomplish, even, this day, all that is desired by him.’”