Musnad Ahmad

It is narrated from Hazrat Ubadah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Laylat al-Qadr occurs in the last ten nights of Ramadan. Whoever stands (in prayer) during these nights seeking its reward, Allah will forgive all his past and future sins. And it occurs in the odd nights, that is, the ninth, seventh, fifth, third, or last night of the last ten nights." He also said: "The sign of Laylat al-Qadr is that the night is bright and radiant, the moon's light is clear and shining, the night is peaceful and calm, and during this night, until morning, the stars are not shot down. Another sign is that in the morning, when the sun rises, it rises straight and evenly, like a full moon, and it has no rays. And on that day, it is forbidden for Satan to rise with the sun."