Musannaf Ibn Abi Shayba 13:3401

Abu Bakr narrated to us, he said: Yahya ibn Adam narrated to us, he said: Abu Shihab narrated to us, from Sufyan, from Khalid ibn Dinar, from al-Harith al-'Ukli, regarding the purchasing of green fodder (qasil) on the condition that he feeds it [to his animals]: He said: If something occupies him from cutting it until it increases [in growth], then there is no harm in it.