A man from Juhaynah informed him that he heard the Prophet ﷺ recite "When the earth is shaken with its earthquake" [Zalzalah 99:1] in the dawn prayer, in both rakahs. He said, "I do not know whether the Messenger of Allah ﷺ forgot, or whether he recited it that way intentionally."
أن رجلا من جهينة أخبره، أنه سمع النبي ﷺ يقرأ في الصبح: {إذا زلزلت الأرض زلزالها} في الركعتين كلتيهما، فلا أدري أنسي رسول الله ﷺ؟ أم قرأ ذلك عمدا.
Abu Dawud (816) narrated it from Ahmad bin Salih, who said, Ibn Wahb told us, Amr bin Abu Hilal informed me, from Muaz bin Abdullah Juhani, and he related it. Its chain is hasan because of Ibn Abu Hilal and his teacher Muaz bin Abdullah Juhani, for the hadith is hasan on their account, and the anonymity of the companion does not harm it.As for what has been reported concerning the virtues of Surah Zalzalah, that it equals half of the Quran, this is daif. It was reported from Anas bin Malik, and Tirmidhi (2893) and others narrated it, but it contains Hasan bin Salm bin Salih Ajli, who is unknown, as Aqeeli and others have said. Tirmidhi said, "This hadith is unusual, we do not know it except through the report of this teacher, Hasan bin Salm, and on this subject there is also a report from Ibn Abbas."Then he narrated it (2894), as did Hakim (1/566), both of them through Yazid bin Harun, who said, Yaman bin Mughira Anazi informed us, Ataa told us, from Ibn Abbas, and he related it. Tirmidhi said, "We do not know it except through the report of Yaman bin Mughira." Hakim said, "Its chain is sahih." Dhahabi commented on this, saying, "Rather, they have declared Yaman daif."I say, it is as he said, for Ibn Main, Abu Hatim, and Abu Zura all declared him daif, and Bukhari said, his hadith is objectionable. Tirmidhi did not grade either of these two hadiths as hasan, even though it was his usual practice to grade such hadiths as hasan, because the weakness in the hadith of Anas is not severe, and it is strengthened by the hadith of Ibn Abbas despite the weakness in it, since it does not contain anyone accused of fabrication. Even so, he did not grade either of them as hasan.As for his statement, "half of the Quran," it means that the Quran covers two matters, matters of this world and its rulings, and matters of the afterlife and its rulings, so this surah equals half of the Quran because it covers the rulings of the afterlife, as Ibn Qayyim stated in Zad Mad (1/317–318), where he said, "It is more fitting that this hadith be sahih."