Al-Matalib al-'Aliyah 2908 — The traits of faith

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) (the narrator of the hadith, Hammad, says: as far as I know, Ibn Abbas (may Allah be pleased with them both) traced this saying back to the Prophet (peace and blessings be upon him) as marfu') that he (peace and blessings be upon him) said: "The firm handholds of Islam and the foundations of the religion are three, upon which Islam has been founded; whoever abandons a single one of them is a disbeliever and his blood is lawful: (first) bearing witness that there is no god worthy of worship except Allah, (second) establishing the obligatory prayer, and (third) fasting in Ramadan." Then Sayyiduna Ibn Abbas (may Allah be pleased with them both) said (explaining further): "You will see a person who is wealthy but does not pay zakah; by this deed he remains a disbeliever (that is, he commits lesser disbelief), yet his blood is not lawful. Likewise you will find a very wealthy person who has not performed Hajj; he too is thereby deemed a disbeliever, yet his blood is not lawful."
Imam Abu Ya'la recorded this hadith in his Musnad; its chain contains Mu'ammal bin Isma'il, who is "sayyi' al-hifz" (of poor memory), and Amr bin Malik al-Nukri is also deemed weak when alone in a narration; therefore this chain is da'if (weak), although there is supporting evidence in other sahih hadith regarding the importance of prayer and fasting.