Musnad Abi Ya'la 5720 — Abu Muhammad (may Allah have mercy on him)

It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that Abu Muhammad (may Allah have mercy on him) said: For a month I carefully observed the prayers of Sayyiduna Abdullah bin Umar (may Allah be pleased with them both), and I heard him reciting "Say: O disbelievers" (Surah al-Kafirun) and "Say: He is Allah, the One" (Surah al-Ikhlas) in the two rak'ahs before the Fajr prayer. Abu Muhammad (may Allah have mercy on him) said: Then I mentioned this to him, and he said: "I watched the Messenger of Allah (peace and blessings be upon him) for a month or twenty-five days (continuously), and in the two rak'ahs before the morning prayer he (peace and blessings be upon him) would recite only 'Say: O disbelievers' and 'Say: He is Allah, the One.' And he (peace and blessings be upon him) also said: 'Indeed, one of these two surahs is equal to a third of the Qur'an and the other is equal to a quarter of the Qur'an: "Say: He is Allah, the One" is equal to a third of the Qur'an, and "Say: O disbelievers" is deemed equal to a quarter of the Qur'an.'"