Muwatta Malik, Book 2, Hadith 96 (USC-MSA) ⓘ

Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahman that on one occasion A'isha, the wife of the Prophet, may Allah bless him and grant him peace, was sleeping with the Messenger of Allah, may Allah bless him and grant him peace, in one garment, when suddenly she jumped up sharply. The Messenger of Allah, may Allah bless him and grant him peace, 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 صلى الله عليه وسلم كَانَتْ مُضْطَجِعَةً مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي ثَوْبٍ وَاحِدٍ وَأَنَّهَا قَدْ وَثَبَتْ وَثْبَةً شَدِيدَةً فَقَالَ لَهَا رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ مَا لَكِ لَعَلَّكِ نَفِسْتِ ‏"‏ ‏.‏ يَعْنِي الْحَيْضَةَ ‏.‏ فَقَالَتْ نَعَمْ ‏.‏ قَالَ ‏"‏ شُدِّي عَلَى نَفْسِكِ إِزَارَكِ ثُمَّ عُودِي إِلَى مَضْجَعِكِ ‏"‏ ‏.‏