Musannaf Ibn Abi Shayba 13:3438

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Isma'il bin Muslim, from al-Harith, he said: Shurayh would not leave a canopy (or roofed structure) under which a horseman could pass with his spear, and he would say: "You have built upon the spear of the horseman."