Musannaf Ibn Abi Shayba 13:1122

Abu Bakr narrated to us, he said: Ibn Abi Za'idah narrated to us, from Isma'il ibn Abi Khalid, he said: 'Amir was asked about the selling of provisions (rizq), and he said: "There is no harm in it, but he should not sell it until he takes possession of it."