The Messenger of Allah ﷺ would glance to his right and left during the prayer without turning his neck to look behind his back.
إن رسول الله ﷺ كان يلحظ في الصلاة يمينا وشمالا، ولا يلوي عنقه خلف ظهره.
Tirmidhi (587) and Nasai (1201) both narrated it through the route of Fadl bin Musa, from Abdullah bin Saeed bin Abu Hind, from Thawr bin Zayd, from Ikrima, from Ibn Abbas, and he related the same wording. The wording given here is Tirmidhi's.Ibn Khuzayma graded it sahih (871, 485), and through his route Ibn Hibban (2288) also narrated it, and Hakim likewise narrated it (1/236-237), all of them through the route of Fadl bin Musa with the same wording. Hakim said, "It is sahih according to the criterion of Bukhari, though the two of them did not narrate it."Tirmidhi found fault with it, saying, "This is a gharib hadith, and Waki differed from Fadl bin Musa in his narration of it." By this he meant what he himself narrated from Mahmud bin Ghaylan, and Imam Ahmad (2486), both from Waki, from Abdullah bin Saeed bin Abu Hind, from a man among the companions of Ikrima, who said, "The Messenger of Allah ﷺ would glance during his prayer without twisting his neck." This narration, besides being disconnected, also contains an unidentified man among the companions of Ikrima.The truth is that this flaw is not damaging, because Fadl bin Musa is a reliable and firmly established narrator, so his addition is accepted according to the principles of the science of hadith. It has already been mentioned that Ibn Khuzayma, Ibn Hibban, and Hakim graded it sahih, and that Imam Ahmad narrated it once as disconnected and another time as connected (2485) from the hadith of Fadl bin Musa. Ibn Qattan also graded it sahih, as mentioned by Zaylai in Nasb Raya (2/90), "This is a sahih hadith, and even though it is gharib, known only through this route, Abdullah bin Saeed and Thawr bin Zayd are both reliable, and Ikrima was relied upon as evidence by Bukhari, so the hadith is sahih." He paid no attention to the criticism based on its being disconnected.There is no contradiction between the hadith of Ayesha and the hadith of Ibn Abbas, as Hakim said, "This turning is different from that one" (meaning the hadith of Ayesha), "for the permissible turning is to glance with one's eye to the right and left." Except that he erred in attributing the hadith of Ayesha to the two Shaykhs, when the correct view is that it is something Bukhari alone narrated.