Mishkat al-Masabih 29 Excellent Qualities and Description of the Prophet كتاب الفضائل والشمائل 60

وَعَنْ أَبِي هُرَيْرَةَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنَّهُ قَالَ: «إِنَّمَا أَنَا رَحْمَةٌ مُهْدَاةٌ» . رَوَاهُ الدَّارِمِيُّ وَالْبَيْهَقِيُّ فِي «شُعَبِ الْإِيمَانِ»

Abu Huraira reported the Prophet as saying, “I am just a mercy which has been bestowed.” Darimi and Baihaqi, in Shu’ab al-iman , transmitted it.