Allah the Exalted sent revelation to His Messenger ﷺ in close succession before his death, until He took him at a time when revelation was at its peak, and then the Messenger of Allah ﷺ passed away.
إن الله تعالى تابع على رسوله ﷺ الوحي قبل وفاته، حتى توفاه أكثر ما كان الوحي، ثم توفي رسول الله ﷺ بعد.
Bukhari related it in the Book of the Virtues of the Quran (4982), and Muslim in the Book of Tafsir (3016), both from Amr bin Muhammad bin Bukayr Naqid, who said, Yaqub bin Ibrahim bin Saad related to us, from his father, from Salih bin Kaysan, from Ibn Shihab, who said, Anas bin Malik informed me, and he narrated it, with both wordings being identical. Muslim joined Amr bin Muhammad with Hasan bin Ali Hulwani and Abd bin Humayd, the three of them narrating from Yaqub bin Ibrahim with his chain of transmission.Hafiz said in Fath al-Bari (8/9), His statement, "until he passed away when the revelation was at its most abundant," meaning the period in which his death occurred was a time when revelation came down more than in any other period. He said, The secret behind this is that after the conquest of Makkah, the delegations increased, and their questions about legal rulings increased, so revelation increased on account of that. What occurred at the end was contrary to what occurred at the beginning, for revelation paused for a while at the start of the prophetic mission, then increased, and during the period of revelation in Makkah, only a few of the long surahs were revealed. Then after the migration, the long surahs containing most of the legal rulings were revealed, so that the final period of the Prophet's life was the period of the most revelation, for the reason mentioned above. End of quote.