Ibn 'Abbas reported that when the Messenger of Allah (ﷺ) fasted on the day of 'Ashura and commanded that it should he observed as a fast, they (his Companions) said to him:

Messenger of Allah, it is a day which the Jews and Christians hold in high esteem. Thereupon the Messenger of Allah (ﷺ) said: When the next year comes, God willing, we would observe fast on the ___ But the Messenger of Allah (ﷺ) died before the advent of the next year. _Muslim

Narrated Ibn `Abbas:

I never saw the Prophet (ﷺ) seeking to fast on a day that he favored more than another except this day, the day of '_____', and this month, meaning the month of Ramadan.

-Sahih al-Bukhari

Ibn'Abbas (Allah be pleased with both of them) reported that the Messenger of Allah (ﷺ) arrived in Medina and found the Jews observing fast on _____________. The Messenger of Allah (ﷺ) said to them:

What is the (significance) of this day that you observe fast on it? They said: It is the day of great (significance) when Allah delivered Moses and his people, and drowned the Pharaoh and his people, and Moses observed fast out of gratitude and we also observe it. Upon this the Messenger of Allah (ﷺ) said: We have more right, and we have a closer connection with Moses than you have; so Allah's Messenger (ﷺ) observed fast (on the day of 'Ashura), and gave orders that it should be observed.-Sahih Muslim

I came to Ibn 'Abbas who was leaning against his sheet of cloth in the Sacred Mosque (al-Masjid al-Haram). I asked him about fasting on the day of 'Ashurah. He said: When you sight the moon of __________, count (the days). When the 9th of ________ comes, fast from the morning. I said: Would Muhammad (ﷺ) observe this fast ? He replied: Thus Muhammad (ﷺ) used to fast.

Once the Prophet (ﷺ) ordered a person on '_________' to announce, "Whoever has eaten, should not eat any more, but fast, and who has not eaten should not eat, but complete his fast (till the end of the day).-Sahih al-Bukhari

Abu Hurairah (May Allah be pleased with him) reported:

The Messenger of Allah (ﷺ) said, "The best month for observing Saum (fasting) next after Ramadan is the month of Allah, the ____________; and the best Salat (prayer) next after the prescribed Salat is Salat at _____)."

[Muslim].

Narrated AbuBakrah:

The Prophet (ﷺ) gave a sermon during his hajj and said: Time has completed a cycle and assumed the form of the day when Allah created the heavens and the earth. The year contains twelve months of which four are sacred, three of them consecutive, viz. ______,_______,___________and also Rajab of Mudar which comes between Jumadah and Sha'ban.

Tasu'a is the _______ of al-Muharram and 'Ashura is the 10th al-Muharram.

_____________________ is the first month of Islamic Calendar.