Those who used to seat someone behind for the protection of the prayer

Hazrat Jahm bin Abi Sabrah says that Hazrat Zubair bin Awam used to seat a man behind him who would take care of his prayer.

Hazrat Muhammad bin Sirin says that Hazrat Umar bin Khattab (may Allah be pleased with him) feared forgetfulness, so when he would pray, he would assign a man to watch over his prayer. Thus, if he saw him standing, he would stand, and if he saw him sitting, he would sit.

Hazrat Rakeen says that I went to Hazrat Asma, she was old and was performing prayer, a woman was saying to her, "Do rukoo, do sajdah."