The Messenger of Allah ﷺ said, "When Ramadan begins, the gates of Hell are shut, the gates of Paradise are opened, and the devils are chained up."
حدثنا قتيبة بن سعيد حدثنا عبد العزيز بن محمد عن أبي سهيل بن مالك عن أبيه
قال رسول الله ﷺ إذا استهل رمضان غلقت أبواب النار وفتحت أبواب الجنة وصفدت الشياطين
Its isnad is sahih. It has already been mentioned with the wording "When Ramadan begins" and "When the month of Ramadan begins," see numbers 7767, 7768, 8669. Bukhari related it in 4/150, as did Muslim in the Book of Fasting, hadith 2, and the rest of the imams.