Abū Ahmad Muhammad bin Ahmad narrated to us, saying: ‘Abdullāh bin Muhammad bin Shīrawayh narrated to us, saying: Ishāq bin Rāhawayh narrated to us, saying: ‘Abdul Malik bin Muhammad azZamārī informed us, saying: Muhammad bin Sa’īd bin Rummānah told me, saying: my father told me, saying: “It was said to Wahb bin Munabbih, “Isn’t the key of Paradise لا إله إلا الله (‘There is no god worthy of worship except Allah’)?” He said “Definitely, but there is no key except that it has teeth, whoever comes to the door with its teeth, it will be opened for him, and whoever does not come to the door with its teeth, it will not be opened for him”.
“[Hilyat al Awliyā’ wa Tabaqāt al Asfiyā’, 4/66]