Syrian President Bashar al-Assad vowed on Friday to "cleanse" the country of Muslim extremists whom he blamed for a deadly blast that killed more than 40 people.
State news agency SANA said the toll from the Thursday bombing had risen to 49, with the Syrian Observatory for Human Rights watchdog putting the number of dead at 46, including prominent pro-regime Sunni cleric Sheikh Mohamed Saeed al-Bouti.
In a statement published by Al Arabiya, Assad called Bouti a "great figure in Syria and the Islamic world" and vowed to "purge our country" of the "forces of dark".
"I swear to the Syrian people that your blood, and that of your grandson and all the martyrs of the homeland, will not be spilled in vain because we will be faithful to your ideas by destroying their extremism and ignorance until we have cleansed the country," Assad said.
The attack killed 84-year-old Buti as he was giving a sermon in a mosque in the heart of Damascus, reports AP.
It was the first time a suicide bomber detonated explosives inside of a mosque in the 2-year-old Syrian conflict.
The Syrian opposition's former foreign affairs spokeswoman Bassma Kodmani told the BBC World Service that the attack was "unprecedented and unjustified" but said that Buti was extremely unpopular in Syria.
"He [Buti] was not a very popular figure in Syria. About a week ago he called on 'Good Muslims' to fight to defend the regime against gangs - as the regime usually describes the rebels. That probably provoked a lot of anger among the revolutionary groups who perceived him as corrupt and controlled entirely by the regime.
"I am not justifying [the attack] I am explaining why the man is hated and the reasons why he was killed. The nature of the attack was absolutely awful and walking into a mosque to do that is unprecedented," Kodmani told the BBC.
An estimated 70,000 people have been killed in Syria's war despite international attempts to stop the bloodshed.