iti vyavasita vipras
tasya rajñah prajataye
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Thus for the sake of a son for King Anga, they decided to offer oblations to Lord Visnu, who is situated in the hearts of all living entities.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
According to sacrificial rituals, animals are sometimes sacrificed in the yajña arena. Such animals are sacrificed not to kill them but to give them new life. Such action was an experiment to observe whether the Vedic mantras were being properly pronounced. Sometimes small animals are killed in a medical laboratory to investigate therapeutic effects. In a medical clinic, the animals are not revived, but in the yajña arena, when animals were sacrificed, they were again given life by the potency of Vedic mantras. The word sipi-vistaya appears in this verse. Sipi means “the flames of the sacrifice.” In the sacrificial fire if the oblations are offered into the flames, then Lord Visnu is situated there in the form of the flames. Therefore Lord Visnu is known as Sipivista.