The Prophet ﷺ said, "When Ramadan arrives, the gates of Paradise are opened, the gates of Hell are closed, and the devils are chained."
حدثنا سليمان قال أنبأنا إسماعيل أخبرني أبو سهيل نافع بن مالك بن أبي عامر عن أبيه
أن النبي ﷺ قال إذا جاء رمضان فتحت أبواب الجنة وغلقت أبواب النار وصفدت الشياطين
Its isnad is sahih. Bukhari and Muslim narrated it, and in one version of Muslim's narration, "The gates of mercy are opened, the gates of Hell are closed, and the devils are chained." Tirmidhi, Ibn Majah, and Ibn Khuzayma in his Sahih also narrated it, from Abu Bakr bin Ayyash, from Amash, from Abu Salih, from Abu Hurairah, and their wording is, "When the first night of the month of Ramadan comes, the devils and the rebellious jinn are shackled." Nasai and Hakim narrated it with wording close to this, and Hakim said, sahih according to the criteria of both Bukhari and Muslim. The meaning of "shackled" (with a doubled letter) is that they are bound with chains.