Ahmad ibn ‘Ubdun narrated to me from Ali ibn Muhammad ibn al-Zubayr, from Ali ibn al-Hasan ibn Faddal, from Ya‘qub ibn Yazid, from Muhammad ibn Abi ‘Umayr, from Jamil ibn Darraj, from Muhammad ibn Muslim: Abu ‘Abdillah عليه السلام said: "The minimum duration of menstruation is three days. If she sees blood before ten days, it is part of the first menstrual period. However, if she sees it after ten days, it is considered part of a new, subsequent menstrual period."