Muwatta Imam Malik Book of Purity, Hadith 96

Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahman that on one occasion A'isha, the wife of the Prophet ﷺ was sleeping with the Messenger of Allah ﷺ in one garment, when suddenly she jumped up sharply. The Messenger of Allah ﷺ said to her, "What's the matter with you? Are you losing blood?", meaning menstruating. She said, "Yes." He said, "Wrap your waist-wrapper tightly about you, and return to your sleeping- place."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ رَبِيعَةَ بْنِ أَبِي عَبْدِ الرَّحْمَنِ، أَنَّ عَائِشَةَ، زَوْجَ النَّبِيِّ ﷺ كَانَتْ مُضْطَجِعَةً مَعَ رَسُولِ اللَّهِ ﷺ فِي ثَوْبٍ وَاحِدٍ وَأَنَّهَا قَدْ وَثَبَتْ وَثْبَةً شَدِيدَةً فَقَالَ لَهَا رَسُولُ اللَّهِ ﷺ " مَا لَكِ لَعَلَّكِ نَفِسْتِ " . يَعْنِي الْحَيْضَةَ . فَقَالَتْ نَعَمْ . قَالَ " شُدِّي عَلَى نَفْسِكِ إِزَارَكِ ثُمَّ عُودِي إِلَى مَضْجَعِكِ " .