Mbh 14.85.1a

"Vaisampayana said, 'Having said these words, Partha set out, following the horse which wandered at its will. The sacrificial steed then turned towards the road that led to the city called after the elephant. Yudhishthira heard from his intelligence-bearers that the steed had turned back. And hearing also that Arjuna was hale and hearty, he became filled with joy.[202] Hearing also the feats, accomplished by Vijaya in the country of the Gandharas as also in another realms, the king became exceedingly glad. Meanwhile, king Yudhishthira the just, seeing that the twelfth day of the lighted fortnight in the month of Magha had come, and noticing also that the constellation was favourable, summoned all his brothers, viz., Bhima and Nakula and Sahadeva. Endued with great energy, the king, O thou of Kuru's race, that foremost of all persons conversant with duties, said these words in proper time. Indeed, that foremost of all speakers, addressing Bhima, the first of all smiters, said;--"Thy younger brother (Arjuna), O Bhimasena, is coming back with the horse. I have learnt this from those men who had followed Arjuna. The time (for the sacrifice) is come. The sacrificial horse is near. The day of full moon of the month of Magha is at hand. The month is about to expire, O Vrikodara. Let, therefore, learned Brahmanas conversant with the Vedas look for a sacrificial spot for the successful accomplishment of the Horse-sacrifice." Thus addressed, Bhima obeyed the royal behest. He became very glad upon hearing that Arjuna of curly hair was about to come back. Then Bhima went out with a number of men well conversant with the rules of laying out sacrificial grounds and constructing buildings. And he took with him many Brahmanas well-versed in all the rites of sacrifices. Bhima selected a beautiful spot and caused it to be duly measured out for laying the sacrificial compound. Numerous houses and mansions were constructed on it and high and broad roads also were laid out.