בבא קמא פרק ו משנה ב

(2) If the owner left it in the the sun, or he left it in the care of a deaf-mute, a shoteh, or a minor, and it escaped and caused damage, he is liable. If he handed them over to the care of a shepherd, the shepherd enters in his place [he assumes responsibility] . If a sheep fell into a garden and derived benefit, he pays from what which it benefited. However, if it had gone down in its usual manner and caused damage, he would pay the damage that it caused. How is recompense payed for the amount of damage? We compare the value of a seah's measurement in the field as it was [before the damage], with what its value is now [after damage]. Rabbi Shimon says: If it consumed ripe fruits, he pays [value of] ripe fruits. If it consumed one se'ah's worth, he pays one se'ah. If two se'ah's worth, two se'ah.