aham suto vam abhavam
prsnigarbha iti srutah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Since I found no one else as highly elevated as you in simplicity and other qualities of good character, I appeared in this world as Prsnigarbha, or one who is celebrated as having taken birth from Prsni.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In the Treta-yuga the Lord appeared as Prsnigarbha. Srila Visvanatha Cakravarti Thakura says, prsnigarbha iti so ’yam treta-yugavataro laksyate.