Musnad Abu Ya'la al-Mawsili 110:22

Abu Yusuf al-Jizi narrated to us, Mu’ammal narrated to us, Hammad bin Zayd narrated to us, ‘Amr bin Malik al-Nukri narrated to us, from Abu al-Jawza’, from Ibn ‘Abbas, who said—and Hammad said: "I do not know it except that he has attributed it to the Prophet (may Allah bless him and grant him peace)"—he said: "The handholds of Islam and the foundations of the religion are three, upon which Islam is established. Whoever abandons one of them is, by that, a disbeliever whose blood is lawful: the testimony that there is no god but Allah, the prescribed prayer, and the fasting of Ramadan." Then Ibn ‘Abbas said: "You find him with much wealth, yet he does not pay Zakat; he remains by that a disbeliever whose blood is lawful. And you find him with much wealth, yet he has not performed Hajj; he remains by that a disbeliever, but his blood is not lawful."