and the ḥadīth was attributed by al-Ḥāfiẓ in "al-Iṣābah" (3/88) to al-Ḥasan ibn Sufyān as well as al-Baghawī through the route of Ibn Lahīʿah. Al-Suyūṭī attributed it to Aḥmad and al-Ṭabarānī in "al-Kabīr," but I did not find it in "Musnad Aḥmad," which is intended when attribution is made to him, and there is no mention of Saʿd ibn al-Mundhir in "al-Musnad." It is with al-Ṭabarānī (5481) through another route from Ibn Lahīʿah. The following ḥadīth also supports the three.

"Recite the Qurʾān in every month, recite it in twenty-five [days], recite it in twenty [days], recite it in fifteen [days], recite it in seven [days], one who recites it in less than three [days] does not understand it." It was narrated by Imām Aḥmad (2/165 and 189) through the route of Hammām from Qatādah from Yazīd ibn ʿAbd Allāh ibn al-Shikhkhīr from ʿAbd Allāh ibn ʿAmr who said: "I said: O Messenger of Allāh! In how many [days] should I recite the Qurʾān? He said: Recite it in a month. I said: I am able to do more than that. He said: Recite it in twenty-five [days]. I said..." [and so on] the ḥadīth. It was also narrated by Abū Dāwūd in a shortened form, and al-Ṭayālisī has the last sentence of it. See "Ṣaḥīḥ Abī Dāwūd" (1257). The ḥadīth has many routes in "al-Musnad," both lengthy and concise, including what was narrated (2/188 and 195) through the route of Shuʿbah from ʿAmr ibn Dīnār from Abū al-ʿAbbās from ʿAbd Allāh ibn ʿAmr who said: The Messenger of Allāh (ṣallá Allāhu ʿalayhi wa-sallam) said to me: (Recite the Qurʾān in a month. I said: I am able to do more than that, and I continued to ask him until he said: Recite the Qurʾān in five days)