Sahih Muslim
The Book of Marriage (Kitab Al-Nikah)
Book Number: 008 / Hadith Number: 3451
'A'isha (Allah be pleased with her) reported: Never did I find any woman more loving to me than Sauda bint Zam'a. I wished I could be exactly like her who was passionate. As she became old, she had made over her day (which she had to spend) with Allah's Messenger (may peace be upon him) to 'A'isha. She said: I have made over my day with you to 'A'isha. So Allah's Messenger (may peace be upon him) allotted two days to 'A'isha, her own day (when it was her turn) and that of Sauda.