Virtues of the Qur'an
66/1. Chapter:
How the Divine Revelation used to be revealed and what was the first thing revealed
Sahih Bukhari
حَدَّثَنَا عَمْرُو بْنُ مُحَمَّدٍ، حَدَّثَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا أَبِي، عَنْ صَالِحِ بْنِ كَيْسَانَ، عَنِ ابْنِ شِهَابٍ، قَالَ أَخْبَرَنِي أَنَسُ بْنُ مَالِكٍ ـ رضى الله عنه ـ أَنَّ اللَّهَ، تَعَالَى تَابَعَ عَلَى رَسُولِهِ صلى الله عليه وسلم قَبْلَ وَفَاتِهِ حَتَّى تَوَفَّاهُ أَكْثَرَ مَا كَانَ الْوَحْىُ، ثُمَّ تُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم بَعْدُ.
Narrated Anas bin Malik: Allah sent down His Divine Inspiration to His Apostle continuously and abundantly during the period preceding his death till He took him unto Him. That was the period of the greatest part of revelation; and Allah's Messenger (ﷺ) died after that.
Reference : Sahih al-Bukhari 4982In-book reference : Book 66, Hadith 4USC-MSA web (English) reference : Vol. 6, Book 61, Hadith 505