Qays bin Saad used to stand before the Prophet ﷺ in the position of a chief of guard before a commander.
أن قيس بن سعد كان يكون بين يدي النبي ﷺ بمنزلة صاحب الشرط من الأمير.
Bukhari related it in "The Rulings" (7155) from Muhammad bin Khalid Dhuhli, [who said] Ansari Muhammad bin Abdullah told us, he said, my father told me, from Thumamah, from Anas bin Malik, and he related it.