When the Messenger of Allah ﷺ had prayed Fajr, he would lie down on his side.
كان رسول الله ﷺ إذا صلى الفجر اضطجع.
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Ibn Majah (1199) narrated it from Umar bin Hisham, who said, Nadr bin Shumayl narrated to us, who said, Shuba informed us, who said, Suhayl bin Abu Salih narrated to me, from his father, from Abu Hurairah, and he related it. Its isnad is sahih.As for what was narrated from Abu Hurairah, who said, the Messenger of Allah said, "When any of you prays the two rakahs before dawn, let him lie down on his right side," this is rejected. Abu Dawud (1261), Tirmidhi (420), and Ahmad (9368) all narrated it through the route of Abdul-Wahid bin Ziyad, who said, Amash narrated to us, from Abu Salih, from Abu Hurairah, and he related it.Abu Dawud added that Marwan bin Hakam said to him, "Does not one of us's walking to the masjid suffice, without having to lie down on his right side?" Abdullah bin Umar bin Maysara (the narrator from Abdul-Wahid in Abu Dawud's version) said, "No." He said, that reached Ibn Umar, so he said, "Abu Hurairah has taken too much upon himself." He said, it was said to Ibn Umar, "Do you reject anything he says?" He said, "No, but he was bold and we were timid." He said, that reached Abu Hurairah, so he said, "What is my fault if I remembered and they forgot?" End.Tirmidhi said, "The hadith of Abu Hurairah is hasan," and in one manuscript, "hasan sahih." Ibn Khuzayma (1120) and Ibn Hibban (2468) graded it sahih, narrating it through the route of Abdul-Wahid bin Ziyad in like manner. Nawawi said in Sharh Muslim (19/6), "Its isnad meets the standard of the two Shaykhs," and he also graded it sahih in Majmu (28/4).I say, Abdul-Wahid bin Ziyad, although he is among the narrators relied upon by the two Shaykhs, some critics have nevertheless criticized him regarding his memory. They said he did not memorize the hadith of Amash well, and therefore they said he alone, among the companions of Amash, related it in this manner, making it a command from the Prophet ﷺ, whereas Suhayl bin Abu Salih narrated it, from his father, from Abu Hurairah, as an action of the Prophet ﷺ, as mentioned before. Likewise, Muhammad bin Ibrahim narrated it from Abu Salih, from Abu Hurairah, describing it as an action of the Prophet ﷺ. Bayhaqi said (3/45), "This is more fitting to be the preserved version, since it agrees with the rest of the narrations from Ayesha and Ibn Abbas." End.Zarkashi said in Nukat ala Muqaddimah Ibn Salah (2/163), "Bayhaqi said, 'Abdul-Wahid contradicted the large number of narrators regarding this hadith, for people only narrated it as an action of the Prophet ﷺ, not as a command from him, and Abdul-Wahid alone, among the trustworthy companions of Amash, used this wording.'" This is how Zarkashi quoted from Bayhaqi, and what is found in Sunan al-Kubra of Bayhaqi is as I have mentioned.Dhahabi said in Mizan, in the biography of Abdul-Wahid bin Ziyad Abdi Basri, one of the well-known figures whom the two Shaykhs relied upon in the Sahihayn while avoiding those rejected narrations held against him, "He narrates from Amash using the wording of direct hearing, from Abu Salih, from Abu Hurairah, 'The Messenger of Allah said, "When any of you prays the two rakahs before dawn, let him lie down on his right side."' Abu Dawud narrated it."Hafiz bin Qayyim quoted from Ibn Taymiya his saying, "This is false, and it is not sahih. Rather, what is sahih from him is the action, not the command to do it. Abdul-Wahid bin Ziyad alone narrated the command, and he erred in it." Zad Mad (319/1).As for the hadith of Ibn Abbas that Bayhaqi referred to, it contains a discontinuity, as he said.