ahuto bhagavan rajña
yajayitva dvijair nrpam
uvasa katicin masan
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Sri Krsna, the Personality of Godhead, being invited to the sacrifices by Maharaja Yudhisthira, saw to it that they were performed by qualified [twice-born] brahmanas. After that, for the pleasure of the relatives, the Lord remained a few months.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Sri Krsna was invited by Maharaja Yudhisthira to look into the supervision of the performances of yajña, and the Lord, to abide by the orders of His elderly cousin, caused the performance of yajñas by learned twice-born brahmanas. Simply taking birth in the family of a brahmana does not make one qualified to perform yajñas. One must be twice-born by proper training and initiation from the bona fide acarya. The once-born scions of brahmana families are equal with the once-born sudras, and such brahma-bandhus, or unqualified once-born scions, must be rejected for any purpose of religious or Vedic function. Lord Sri Krsna was entrusted to look after this arrangement, and perfect as He is, He caused the yajñas to be performed by the bona fide twice-born brahmanas for successful execution.