Musannaf Ibn Abi Shayba 35:220

Ibn Idris narrated to us, from ‘Asim ibn Kulayb, from his father, who said: We were in the military expeditions, and no one was appointed over us except the companions of the Messenger of Allah, may Allah bless him and grant him peace. We were in Persia, and a man from Muzaynah, one of the companions of the Prophet, may Allah bless him and grant him peace, was over us. The whetstones became expensive for us, until we were buying a whetstone for two or three young sheep. This man stood among us and said: "Indeed, this day we have reached, the whetstones have become expensive for us, until we were buying a whetstone for two or three young sheep." Then the Prophet, may Allah bless him and grant him peace, stood among us and said: "Indeed, the whetstone is fulfilled by what is fulfilled from it by the two-year-old sheep."