Sahih al-Bukhari, Hadith 3146 ⓘ
Narrated Anas: The Prophet said, "I give to Quraish people in order to let them adhere to Islam, for they are near to their life of Ignorance (i.e. they have newly embraced Islam and it is still not strong in their hearts."
حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " إِنِّي أُعْطِي قُرَيْشًا أَتَأَلَّفُهُمْ، لأَنَّهُمْ حَدِيثُ عَهْدٍ بِجَاهِلِيَّةٍ " .
also referenced under: Book 57, Hadith 54 (In-Book) & Volume 4, Book 53, Hadith 374 (USC-MSA)