Musannaf Ibn Abi Shayba 13:1185

Abu Bakr narrated to us, he said: Hatim ibn Isma'il narrated to us, from Ja'far, from his father, he said: I heard al-Nu'man ibn Murrah narrating from Sa'id ibn al-Musayyib, he said: I saw Ali build an enclosure for the lost animals. He would feed them fodder that would neither make them fat nor let them become thin, from the public treasury (Bayt al-Mal). They would stretch their necks [looking out]. Whoever established proof for a thing, he would take it; otherwise, he would leave it in its state and would not sell it. Sa'id ibn al-Musayyib said: If I were in charge of the affairs of the Muslims, I would do the same.