The Messenger of Allah ﷺ said, "When Ramadan arrives, the gates of Paradise are opened, the gates of Hell are closed, and the devils are chained up."
أن رسول الله ﷺ قال: إذا جاء رمضان فتحت أبواب الجنة، وغلقت أبواب النار، وصفدت الشياطين.
Bukhari narrated it in the Book of Fasting (1898), and Muslim in the Book of Fasting (1079), both from Qutayba, who said, Ismail bin Jafar narrated to us, from Abu Suhayl, from his father, from Abu Hurairah, and he related it. The wording is Muslim's, and Bukhari confined himself to the first sentence of the hadith.