How many Ramadaans did the Messenger of Allaah (peace and blessings of Allaah be upon him) fast?

Praise be to Allah.

The scholars are unanimously agreed that fasting the month of Ramadaan was enjoined in Sha’baan 2 AH, and that the Prophet (peace and blessings of Allaah be upon him) fasted nine Ramadaans, because he (peace and blessings of Allaah be upon him) died in Rabee’ al-Awwal 11 AH. 

It says in al-Insaaf: 

Fasting Ramadaan was enjoined in 2 AH according to scholarly consensus. The Messenger of Allaah (peace and blessings of Allaah be upon him) fasted nine Ramadaans according to scholarly consensus. 

Al-Nawawi said in al-Majmoo’: 

The Messenger of Allaah (peace and blessings of Allaah be upon him) fasted Ramadaan for nine years, because it was enjoined in Sha’baan 2 AH, and the Prophet (peace and blessings of Allaah be upon him) died in Rabee’ al-Awwal 11 AH. 

See also Majmoo’ Fataawa by Shaykh al-Islam Ibn Taymiyah, 2/20.