(٢) It is sometimes suggested that the main reason for opposition was the merchants’ fear that the new religion would destroy the recognition of the Ka’bah as a sanctuary, but this is unlikely. Certainly attacks on idols appeared in the Qur'an, and Islam began to be characterized by the insistence that “there is no god but God” (Allah) , but no attack was made on the Ka’bah, and the idols mentioned had their chief shrines elsewhere. (٣) In the summer of , men from Medina, visiting Mecca for the annual pilgrimage to the Ka’bah (still a pagan shrine) , secretly professed themselves Muslims to Muhammad and went back to make propaganda for him at Medina.