masi masiha yo balih
svam svam bhagam prayacchanti
nagah parvani parvani
Sukadeva Gosvami said: To avoid being eaten by Garuda, the serpents had previously made an arrangement with him whereby they would each make a monthly offering of tribute at the base of a tree. Thus every month on schedule, O mighty-armed King Pariksit, each serpent would duly make his offering to that powerful carrier of Visnu as a purchase of protection.
Srila Sridhara Svami has given an alternate explanation of this verse. Upaharyaih may also be translated as “by those who are to be eaten,” and sarpa-janaih as “those human beings who were dominated by or who belonged to the serpent race.” According to this reading, a group of human beings had fallen under the control of the serpents and were prone to be eaten by them. To avoid this, the human beings would make a monthly offering to the serpents, who in turn would offer a portion of that offering to Garuda so that he would not eat them. The particular translation given above is based on the commentary of Srila Sanatana Gosvami and the translation by Srila Prabhupada in his Krsna, the Supreme Personality of Godhead. In any case, all the acaryas agree that the serpents purchased protection from Garuda.