Musnad Abu Ya'la al-Mawsili 155:382

Bishr ibn al-Walid al-Kindi narrated to us, Qaza'ah ibn Suwayd narrated to us, from 'Amr ibn Dinar, from Abu Hurayrah, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever says 'There is no god but Allah' with certainty, enters Paradise."