[7/1556] al-Kafi: Muhammad b. Yahya from Ahmad b. Muhammad b. Isa from Muhammad b. Khalid and al-Husayn b. Sa’id all together from al-Nadhr b. Suwayd from Yahya al-Halabi from Abi Usama who said
I heard Aba Abdillah عليه السلام say: Whoever recites Qul Huwa l-Llāhu Aḥad a hundred times when he betakes himself to his bed-spread (i.e. before sleeping) - it is forgiven for him what he has committed (of sins) fifty years prior to that. Yahya said: I asked Sama’a about that, so he (i.e. Sama’a) said: Abu Basir narrated (it) to me and said ‘I heard Aba Abdillah saying that’ and he (i.e. the Imam) added: O Aba Muhammad (i.e. Abu Basir) indeed if you were to try it you will find it to be true .