It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that when the Messenger of Allah (peace and blessings be upon him) married her, he said to her: "If you wish, I will stay with you for seven days; (but) if I give you seven days, then I will give seven days to each of the rest of my wives as well."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19810