Bhagavad Gita 3.10

3.10 The Creator, having in the beginning (of creation) created mankind together with sacrifice, said, "By this shall ye propagate; let this be the milch cow of your desires (the cow which yields all the desired objects)."

In the beginning of creation, the Lord of all creatures sent forth generations of men and demigods, along with sacrifices for Viṣṇu, and blessed them by saying, “Be thou happy by this yajña [sacrifice] because its performance will bestow upon you everything desirable for living happily and achieving liberation.”