Umm Salama reported that she heard Allah's Messenger (ﷺ) 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.
Source: sunnah.com
Other translations
Arabic
وَحَدَّثَنِي أَبُو مَعْنٍ الرَّقَاشِيُّ، وَأَبُو بَكْرِ بْنُ نَافِعٍ وَعَبْدُ بْنُ حُمَيْدٍ قَالُوا حَدَّثَنَا أَبُو عَامِرٍ - وَهُوَ عَبْدُ الْمَلِكِ بْنُ عَمْرٍو - حَدَّثَنَا أَفْلَحُ بْنُ سَعِيدٍ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ رَافِعٍ، قَالَ كَانَتْ أُمُّ سَلَمَةَ تُحَدِّثُ أَنَّهَا سَمِعَتِ النَّبِيَّ صلى الله عليه وسلم يَقُولُ عَلَى الْمِنْبَرِ وَهِيَ تَمْتَشِطُ " أَيُّهَا النَّاسُ " . فَقَالَتْ لِمَاشِطَتِهَا كُفِّي رَأْسِي . بِنَحْوِ حَدِيثِ بُكَيْرٍ عَنِ الْقَاسِمِ بْنِ عَبَّاسٍ .
sunnah.com