Musannaf Ibn Abi Shayba 28:1054

Waki’ narrated to us, he said: Isma’il bin Abi Khalid narrated to us, from Qays bin Abi Hazim, who said: ‘Amr bin Ma’di Karib used to pass by us on the day of al-Qadisiyyah while we were in rows, and he would say: “O assembly of Arabs, be lions, intense, [and] sufficient in your affair; for the Persian is [but] a goat after he throws his spear.”