Soundness of the hadeeth “Sincerity is one of My secret blessings”
It was narrated by al-Qazweeni in his Musalsalaat, as al-Iraaqi said inTakhreej Ihyaa’ ‘Uloom al-Deen, 4/365, from the hadeeth of Hudhayfah (may Allaah be pleased with him). But its isnaad includes Ahmad ibn ‘Ataa’ al-Hujaymi and ‘Abd al-Wahid ibn Zayd, both of whom are matrook (i.e., their hadeeth is not accepted).
It was also narrated by al-Daylami in Musnad al-Firdaws, 3/187, from ‘Ali and Ibn ‘Abbaas.
Al-Haafiz ibn Hajar said in Fath al-Baari, 4/109, (it is) a waahin jiddan hadeeth (i.e., very flimsy).