It is narrated from Sayyiduna Utbah bin Farqad (may Allah be pleased with him) that he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "When the month of Ramadan comes, the gates of Paradise are opened, the gates of Hell are closed, the devils are chained, and a caller calls out: O seeker of good, come forward (to virtue), and O seeker of evil, refrain (from sin), until the month comes to an end."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Ata (may Allah have mercy on him) from al-Sha'bi (may Allah have mercy on him) except Abd al-Salam (may Allah have mercy on him), and Abu Bilal (may Allah have mercy on him) is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الألف / 1563
Hadith Takhrij«أخرجه النسائي فى «المجتبى» برقم: 2106 / 4، والنسائي فى «السنن الكبرى» برقم: 2428، وعبد الرزاق فى «مصنفه» برقم: 7386، والطبراني فى «الكبير» برقم: 325، 326، 327»