Which day is ‘Aashooraa..?

An-Nawawi (may Allaah have mercy on him) said:  
“‘Aashooraa´ and Taasoo‘aa´ are two elongated names [the 
vowels are elongated] as is stated in books on the Arabic
language.

 Our companions said: ‘Aashooraa´ is the tenth 
day of Muharram and Taasoo‘aa´ is the ninth day. This is
our opinion, and that of the majority of scholars. This is 
the apparent meaning of the ahaadeeth and is what we understand from the general wording. It is also what is usually understood by scholars of the language.” (al-Majmoo’)  
‘Aashooraa´ is an Islamic name that was not known at the time of 
Jaahiliyyah. (Kashshaaf al-Qinaa’, part 2, Sawm Muharram).  
Ibn Qudaamah (may Allaah have mercy on him) said:  
“‘Aashooraa´ is the tenth day of Muharram. This is the 
opinion of Sa’eed ibn al-Musayyib and al-Hasan. It was 
what was reported by Ibn ‘Abbaas, who said:  ‘The Messenger of Allaah (peace and  blessings of Allaah be upon 
him) commanded us to fast ‘Aashooraa´, the tenth day of 
Muharram.’ (Reported by al-Tirmidhi, who said, a saheeh 
hasan hadeeth).  
It was reported that Ibn ‘Abbaas said: ‘The ninth,’ and reported 
that the Prophet (peace and blessings of Allaah be upon him) 
used to fast the ninth. (Reported by Muslim). ‘Ataa´ reported that
he said, ‘Fast the ninth and the tenth, and do not be like the 
Jews.’ If this is understood, we can say on this basis that it is 
mustahabb (encouraged) to fast  on the ninth and the tenth, for 
that reason. This is what Ahmad said, and it is the opinion of 
Ishaaq.” 


It is Mustahabb (encouraged) to  fast Taasoo'aa' with 'Aashooraa
'Abd-Allaah ibn 'Abbaas (may Allaah be pleased with them both) 
said: 
“When the Messenger of Allaah (peace and blessings of
Allaah be upon him) fasted on ‘Aashooraa´ and commanded the Muslims to fast as well, they said, ‘O Messenger of Allaah, it is a day that is venerated by the Jews 
and Christians.’ The Messenger of Allaah (peace and 
blessings of Allaah be upon him) said, ‘If I live to see the 
next year, in shaa Allaah, we will fast on the ninth day 
too.’ But it so happened that the Messenger of Allaah 
(peace and blessings of Allaah be upon him) passed 
away before the next year came.” (Reported by Muslim,
1916). 
Al-Shaafi‘i and his companions, Ahmad, Ishaaq and others said: 
“It is mustahabb to fast on both the ninth and tenth days, 
because the Prophet (peace and blessings of Allaah be 
upon him) fasted on the tenth, and intended to fast on the 
ninth.” 
On this basis it may be said that there are varying degrees of fasting ‘Aashooraa´, the least of which is to fast only on the tenth 
and the best of which is to fast the ninth as well. The more one 
fasts in Muharram, the better it is.