(25) It was narrated on the authority of Ibn Ad-Daylami, may Allaah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: "Indeed, the most virtuous act of worship is to think good of Allah, The Almighty, for Allah, The Almighty, says: ‘I am as My slave thinks I am."
The Verification of the Hadeeth: Its Isnaad (i.e. chain of transmission) is weak.
It was reported by At-Tabaraani in Musnad Ash-Shaamyeen (509), Al-Baghawi as in Al-Jaami‘ Al-Kabeer (882), Kanz Al-‘Umaal (5843) from the route of Yazeed ibn Sinaan Abi Farwah Al-Jazri from ‘Urwah ibn Ruwaym from Abi Idrees Al-Khawalaani from Ibn Ad-Daylami. Its Isnaad is weak because of Yazeed ibn Sinaan about whom Ibn Ma‘een said: "Kufi people reported from him and he is not trustworthy."
Imam Al-Bukhaari, may Allaah have mercy upon him, said about him: "He is very weak." and An-Nasaa‘i said: “He is not strong.” (1).
Refer to Dha‘eef Al-Jaami‘ (1399).
___________________________________
(1) Refer to Tahtheeb Al-Kamaal (27/20), Adh-Dhu`faa' Al-Kabeer (4/382), Al-Mizaan (4/562) and At-Tahtheeb (9/463).