SB 9.14.49
pururavasa evasit
trayi treta-mukhe nrpa
agnina prajaya raja
lokam gandharvam eyivan
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O Maharaja Pariksit, at the beginning of Treta-yuga, King Pururava inaugurated a karma-kanda sacrifice. Thus Pururava, who considered the yajñic fire his son, was able to go to Gandharvaloka as he desired.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In Satya-yuga, Lord Narayana was worshiped by meditation (krte yad dhyayato visnum). Indeed, everyone always meditated upon Lord Visnu, Narayana, and achieved every success by this process of meditation. In the next yuga, Treta-yuga, the performance of yajña began (tretayam yajato mukhaih). Therefore this verse says, trayi treta-mukhe. Ritualistic ceremonies are generally called fruitive activities. Srila Visvanatha Cakravarti Thakura says that in Treta-yuga, beginning in the Svayambhuva-manvantara, ritualistic fruitive activities were similarly manifested from Priyavrata, etc.
Thus end the Bhaktivedanta purports of the Ninth Canto, Fourteenth Chapter, of the Srimad-Bhagavatam, entitled “King Pururava Enchanted by Urvasi.”