Sayyiduna Abu Mas'ud (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Is any one of you unable to recite a third of the Qur'an?" This weighed heavily upon them, so he (peace and blessings be upon him) said: "'Allah, the One, the Self-Sufficient' is a third of the Qur'an."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14778
Sayyiduna Abu Mas'ud (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Is it difficult for any one of you to recite a third of the Qur'an every night?" The Companions said: O Messenger of Allah, which of us has the strength for that? He (peace and blessings be upon him) said: "'Say: He is Allah, the One.'"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14779
Sayyiduna Abu Mas'ud al-Ansari (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Is any one of you unable, or he said: overcome, to recite a third of the Qur'an?" We said something to him about that, so he (peace and blessings be upon him) said: "'Say: He is Allah, the One.'"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14780
It is narrated from Sayyiduna Abu Mas'ud al-Badri (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 in one night?" The Companions said: O Messenger of Allah, do we have the strength to recite a third of the Qur'an? He (peace and blessings be upon him) said: "Is any one of you unable to recite 'Say: He is Allah, the One'?"
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14781