The Prophet ﷺ said, "Is any of you incapable of reciting a third of the Quran every night?"They asked, "Messenger of Allah, who can manage that?"He replied, "Say, He is Allah, the One" [Ikhlas 112:1].
عن النبي ﷺ قال: أيعجز أحدكم أن يقرأ ثلث القرآن كل ليلة؟ قالوا: ومن يطيق ذلك يا رسول الله؟ قال: {قل هو الله أحد}.
Nasai narrated it in Al-Kubra (10511), and Bazzar (1866), and Ibn Hibban (2576), all of them through the route of Shubah, from Ali bin Mudrak, who said, Ibrahim Nakhai narrated to us, from Rabi bin Khuthaym, from Ibn Masud, and he mentioned it. Its chain of transmission is sahih.It has also been narrated as stopped (mawquf). Darimi narrated it (3476) through two routes, from Asim, from Zirr, from Ibn Masud as his own words, and the ruling goes to whoever raised it (to the Prophet).