Sahih Muslim
The Book Pertaining to the Excellent Qualities of the Holy Prophet (may Peace be upon them) and His Companions (Kitab Al-Fadail)
Book Number: 030 / Hadith Number: 5687
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.