Maliks Muwatta Book 2, Hadith Number 100.
Section : The Purity of a Menstruating Woman.
Yahya related to me from Malik from Abdullah ibn Abi Bakr from his paternal aunt from the daughter of Zayd ibn Thabit that she had heard that women used to ask for lamps in the middle of the night to check their purity. She would criticise them for this saying, “Women never used to do this,” i.e. in the time of the companions.