Ahmad ibn Muhammad narrated from Ja‘far ibn Muhammad, from Khalaf ibn Hammad, who said: I said to Abu al-Hasan al-Madhi عليه السلام: "May I be your ransom! One of your followers asked me to inquire about an issue on his behalf. Do you permit me to ask it?" Imam عليه السلام replied: "Proceed." I said: "May I be your ransom! A man married a girl or purchased a female slave, and she either had already begun menstruating or had not yet menstruated. Then, when he consummated the marriage with her, she experienced profuse bleeding that lasted for several days and nights. She was examined by midwives, some of whom said it was menstrual blood, while others said it was from the rupture of the hymen." Imam عليه السلام smiled and said: "If it is from menstruation, then her husband must refrain from her, and she must refrain from performing prayers. However, if it is from the rupture of the hymen, then she should perform ablution (wudu) and pray, and her husband may approach her if he wishes." I said: "May I be your ransom! How can she determine whether it is menstrual blood or from the rupture of the hymen?" Imam عليه السلام said: "O Khalaf, this is a secret of Allah سبحانه وتعالى, so do not disclose it. She should insert a piece of cotton and then remove it. If the cotton comes out with blood encircling it (i.e., forming a ring), it is from the rupture of the hymen. However, if it comes out soaked in blood, it is menstrual blood."