Abu Hutakiya narrates: Sayyiduna Umar ibn Khattab (may Allah be pleased with him) said:“Who was with us on the day of Qaahah (the name of a specific valley)? When a rabbit was presented to the Prophet Muhammad (peace and blessings be upon him), Sayyiduna Abu Dharr al-Ghifari (may Allah be pleased with him) replied: I was. A Bedouin brought a rabbit to the Prophet Muhammad (peace and blessings be upon him) and said: O Messenger of Allah! I have seen that it bleeds (i.e., it menstruates). The narrator says: So the Prophet Muhammad (peace and blessings be upon him) refrained from it, he did not eat it, and he instructed his companions to eat it. That Bedouin also withdrew, he did not eat it either. He said: I am fasting. The Prophet Muhammad (peace and blessings be upon him) asked:“According to what calculation do you fast?”He replied: Three days in every month. The Prophet Muhammad (peace and blessings be upon him) said:“Why do you not fast on the bright days? On the 13th, 14th, and 15th.”