Qays bin Saad used to stand before the Prophet ﷺ in the position of a chief of guard to a commander.
أن قيس بن سعد كان يكون بين يدي النبي ﷺ بمنزلة صاحب الشرط للأمير.
Bukhari (7155) narrated it from Muhammad bin Khalid Dhuhli, who said, Muhammad Ansari narrated to us, who said, my father narrated to us, from Thumama, from Anas, who mentioned it.