Mbh 3.37.1a

Vaisampayana said, “After some time, Yudhishthira the just, remembering the command of the Muni (Vyasa) and calling unto himself that bull among men--Arjuna--possessed of great wisdom, addressed him in private. Taking hold of Arjuna’s hands, with a smiling face and in gentle accents, that chastiser of foes--the virtuous Yudhishthira--apparently after reflecting for a moment, spake these words in private unto Dhananjaya, ‘O Bharata, the whole science of arms dwelleth in Bhishma, and Drona, and Kripa, and Karna, and Drona’s son. They fully know all sorts of Brahma and celestial and human and Vayavya weapons, together with the modes of using and warding them off. All of them are conciliated and honoured and gratified by Dhritarashtra’s son who behaveth unto them as one should behave unto his preceptor. Towards all his warriors Dhritarashtra’s son behaveth with great affection; and all the chiefs honoured and gratified by him, seek his good in return. Thus honoured by him, they will not fail to put forth their might. The whole earth, besides, is now under Duryodhana’s sway, with all the villages and towns, O son of Pritha, and all the seas and woods and mines! Thou alone art our sole refuge. On thee resteth a great burden. I shall, therefore, O chastiser of all foes, tell thee what thou art to do now. I have obtained a science from Krishna Dwaipayana. Used by thee, that science will expose the whole universe to thee. O child, attentively receive thou that science from me, and in due time (by its aid) attain thou the grace of the celestials. And, O bull of the Bharata race, devote thyself to fierce asceticism. Armed with the bow and sword, and cased in mail, betake thyself to austerities and good vows, and go thou northwards, O child, without giving way to anybody. O Dhananjaya, all celestial weapons are with Indra. The celestials, from fear of Vritra, imparted at the time all their might to Sakra. Gathered together in one place, thou wilt obtain all weapons.