The Prophet ﷺ said in his sermon, while resting his back against the Kaabah, "No Muslim shall be killed in retaliation for a disbeliever, nor shall anyone under a covenant be killed during the term of his covenant."
حدثنا وكيع حدثنا خليفة بن خياط
أن النبي ﷺ قال في خطبته وهو مسند ظهره إلى الكعبة لا يقتل مسلم بكافر ولا ذو عهد في عهده
Its isnad is sahih. Khalifa bin Khayat Basri Usfuri, Abu Hubayra, is trustworthy. Ibn Hibban mentioned him in Ath-Thiqat, and Bukhari included his biography in Al-Kabir 2/1/175, saying that he heard from Amr bin Shuayb, and that Shabab's grandfather heard from him, meaning Waki and Amr bin Mansur heard from him. Al-Hafiz gave his biography in Al-Tahdheeb 3:161, describing him as a distinguishing case, meaning that he has no narration in the six books. He mentioned that Abu Walid Tayalisi narrated from him, and gave his biography in Al-Tajil 177, adding among those who narrated from him Abdul-Samad. His narration will come at 6970.As for Bukhari's statement "Shabab's grandfather," he means that this man was the grandfather of Khalifa bin Khayat bin Khalifa Usfuri, Abu Amr, nicknamed Shabab (with a short "a" on the shin and an unstressed ba). This grandson was one of Bukhari's teachers, and his biography appears in Al-Tahdheeb 160-161 and Al-Kabir 2/1/176.Part of this hadith has already appeared in abbreviated form at 6662, through the narration of Sulayman bin Musa from Amr bin Shuayb, and we noted there its sourcing both in full and in abbreviated form. See also Al-Talkhees 336.