It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) or another Companion (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Is any one of you unable to recite a third of the Qur'an?" The Companions (may Allah be pleased with them) said: "Who has the ability to do that?" He (peace and blessings be upon him) said: "Is any one of you not able to recite 'Say: He is Allah, the One'? Indeed, this surah is equal to a third of the Qur'an."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Abu Hasin except Qays, and no one narrated it from Qays except Ibn al-Salt. His nephew Ahmad bin al-Hajjaj is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 5359
Hadith Takhrij«أخرجه ابن حبان فى «صحيحه» برقم: 2576، والنسائي فى «السنن الكبرى» برقم: 10443، 10442، 10441، 10452، والدارمي فى «مسنده» برقم: 3476، 3477، والبزار فى «مسنده» برقم: 1855، 1866، والطحاوي فى «شرح مشكل الآثار» برقم: 1211، والطبراني فى «الكبير» برقم: 8669، 10245، 10318، 10484، 10485، والطبراني فى «الأوسط» برقم: 741، 4783، 8480»