Sahih Muslim Book 30, Hadith Number 5687.

Chapter : The cistern of our Apostle (may peace be upon him) and its characteristics.

Umm Salama reported that she heard Allah’s Apostle (may peace be upon him) saying this as he was sitting on the pulpit and she was getting her hair combed. (He uttered these words): “O people.” And she said to one who was combing: Leave my head; the rest of the hadith is the same.