I heard the Prophet ﷺ say on the day of the conquest of Makkah, "This city will never be invaded again after today until the Day of Resurrection."
سمعت النبي ﷺ يوم فتح مكة يقول: لا تغزى هذه بعد هذا بعد اليوم إلى يوم القيامة.
Tirmidhi (1611), Ahmad (15404), and Hakim (3/627) all narrated it from the hadith of Zakariya bin Abu Zaida, from Shaybi, from Harith bin Malik bin Barsa, who related it. Tirmidhi said, "This is a hasan sahih hadith, and it is the hadith of Zakariya bin Abu Zaida from Shaybi, and we do not know it except through his narration."It appears that Shaybi had two teachers for this hadith, Harith bin Malik bin Barsa, who used to narrate the hadith about the conquest of Makkah, and Abdullah bin Mutee, who used to narrate from his father the hadith about the conquest of Makkah as well as the hadith about the execution of the Qurayshi man. Sometimes he would combine the two narrations, and other times he would separate them.The meaning of the hadith is that no Qurayshi will be killed for disbelief or apostasy after they entered Islam on the day of the conquest. It does not mean that they will never be killed unjustly through execution, for what happened to Quraysh after that is well known. This was pointed out by Nawawi.Sufyan bin Uyayna said that they will never disbelieve again, and will never be fought on account of disbelief. This was mentioned by Tahawi in Mushkil Athar (2/228-229). Likewise, his statement, "Makkah will not be fought against after today," means fought on account of disbelief.