The Prophet ﷺ said, "Fast three days of each month."The man replied, "I am able to do more than that."He kept asking for more until the Prophet ﷺ said, "Fast one day and break your fast the next."Then the Prophet ﷺ said to him, "Recite the Quran once every month."The man replied, "I am able to do more than that."He kept asking for more until the Prophet ﷺ said, "Recite the Quran once every three days."
حدثنا محمد بن جعفر حدثنا شعبة عن مغيرة سمعت مجاهدا يحدث
عن النبي ﷺ أنه قال صم من الشهر ثلاثة أيام قال إني أطيق أكثر من ذلك قال فما زال حتى قال صم يوما وأفطر يوما فقال له اقرإ القرآن في كل شهر قال إني أطيق أكثر من ذلك قال فما زال حتى قال اقرإ القرآن في كل ثلاث
Its chain of transmission is sahih. Mughira is Ibn Miqsam Dabbi, whose reliability was established earlier at 1838, and I will add here that Bukhari mentioned him in Kabir 1/4/322. The hadith appears in shortened form at 6477 and 6764. See also 6843 and 6862.