"when the first night of ramadhan comes, the devils & rebellious jins are put in chains & the door of hell are closed, none of them remains open. The door of heaven are open & none of them remains closed. And a caller calls, 'O the seeker of goodness, come forward and 'O the seeker of evil, desist. And allah has(many) who will be freed from hell'. This announcement is made every night. (al-Tirmidhi, hadith no.618)