Sahih Muslim
The Book of Menstruation (Kitab Al-Haid)
Book Number: 003 / Hadith Number: 734
Anas reported: (The people) stood up for the night prayer when a man spoke forth: I need to say something. The Apostle of Allah (may peace be upon him) entered into secret conversation with him, till the people dozed off or some of the people (dozed off), and then they said the prayer.