Abu Abdullah ibn Ayyash said: Ahmad ibn Ziyad al-Hamadhani and Ali ibn Muhammad al-Tustari narrated to me, saying: Muhammad ibn al-Layth al-Makki narrated to us, saying: Abu Ishaq ibn Abdullah al-Alawi al-Uraydi narrated to me, saying: “And there was uncertainty in my chest regarding which days are to be fasted, so I went to our master Abu al-Hasan Ali ibn Muhammad عليه السلام, peace be upon him, while he was in Sarba, and I did not disclose that (question) to anyone from the creation of Allah سبحانه وتعالى. So I entered upon Imam عليه السلام, and when he saw me, the Imam عليه السلام, peace be upon him, said: “O Abu Ishaq, you have come to ask me about ‘the days on which fasting is observed’. These days of fasting are divided in four; (1) The first of them is the day of twenty-seventh of Rajab, the day on which Allah سبحانه وتعالى, Exalted, sent Muhammad, may Allah سبحانه وتعالى bless him and his family, to His سبحانه وتعالى creation as a mercy to the worlds; (2) And the day of the birth of the Prophet صلى الله عليه وعلى آله وسلم, may Allah سبحانه وتعالى bless him and his family, and it is the seventeenth of the month of Rabi al-Awwal; (3) And the day of the twenty-fifth of Dhu al-Qadah, in which the Ka’aba was spread out; (4) And the day of al-Ghadeer, in which the Messenger of Allah سبحانه وتعالى, may Allah سبحانه وتعالى bless him and his family, established his brother Imam Ali عليه السلام, peace be upon him, as a standard for the people and an Imam after him.” I (narrator) replied: “You have spoken the truth, may I be made your ransom. It is indeed for this reason that I came to you. I bear witness that you are indeed the Proof of Allah سبحانه وتعالى over His سبحانه وتعالى creation.”