Tirmidhi, Ibn Maajah and Ibn Khuzaymah narrated in one report:
“When the first night of the month of Ramadaan comes, the devils and rebellious jinn are chained up and the gates of Hell are closed, and not one gate of it is opened. The gates of Paradise are opened and not one gate of it is closed. And a caller cries out: ‘O seeker of good, proceed; O seeker of evil, desist. And Allaah has those whom He redeems from the Fire, and that happens every night.”
Classed as Hadith (Hasan Saheeh al-Jaami’, 759.