Hammad bin Zayd حماد بن زيد بن درهم الأزدي الأزرق · The Book of Leading the Prayer (Al-Imamah)

"The Iqamah for prayer was said, and the Messenger of Allah (ﷺ) was conversing privately with a man, and did not commence the prayer until the people slept."

"The Messenger of Allah (ﷺ) used to enjoin upon us to make the prayer short, but he would lead us in prayer and recite As-Saffat."

"When the Iqamah for prayer is said, there is no prayer except the prescribed prayer."