But when Aeetes had set down in their midst the adamantine plough and the oxen, which breathed the flame of blazing fire from their tawny jaws and pounded the ground in turn with bronze hooves, he led them up and brought them to the yoke by himself. Stretching out straight furrows he drove them, and he split open the back of the clodded earth a fathom deep. And he spoke thus: "Let the king who commands the ship finish this work for me, and let him carry off the imperishable coverlet, the fleece glittering with its golden fringe."

Aeetes sets the test by doing it first. He plants an adamantine plough in the field, brings out bulls that breathe fire and strike the earth with bronze hooves, yokes them alone and drives a furrow a fathom deep, about the span of a man's outstretched arms. Only then does he speak, and his terms are a king's: let the captain of the ship do the same, and take the fleece. He calls the prize ἄφθιτον στρωμνάν, an "imperishable coverlet." Pindar has already told how it came to Colchis. Phrixus rode the golden ram there, and Pelias told Jason that a dream had brought him Phrixus' command to fetch his soul and the ram's deep fleece home (lines 159–163). The fleece Jason was sent for turns out to be Aeetes' prize for a task no one was expected to survive.