The Prophet sallahu alayhi was salam said:
إِذَا كَانَ أَوَّلُ لَيْلَةٍ مِنْ شَهْرِ رَمَضَانَ صُفِّدَتِ الشَّيَاطِينُ وَمَرَدَةُ الْجِنِّ وَغُلِّقَتْ أَبْوَابُ النَّارِ فَلَمْ يُفْتَحْ مِنْهَا بَابٌ. وَفُتِّحَتْ أَبْوَابُ الْجَنَّةِ فَلَمْ يُغْلَقْ مِنْهَا بَابٌ وَيُنَادِي مُنَادٍ يَا بَاغِيَ الْخَيْرِ أَقْبِلْ وَيَا بَاغِيَ الشَّرِّ أَقْصِرْ وَلِلَّهِ عُتَقَاءُ مِنَ النَّارِ وَذَلِكَ كُلَّ لَيْلَةٍ
On the first night of the month of Ramadan, the Shayatin are shackled, the jinns are restrained, the gates of the Fires are shut such that no gate among them would be opened. The gates of Paradise are opened such that no gate among them would be closed, and a caller calls: ‘O seeker of the good; come near!’ and ‘O seeker of evil; stop! For there are those whom Allah frees from the Fire.’ And that is every night.
[Reported by Tirmidhi and graded Saheeh by Al-Albani in Saheeh Tirmidhi no. 682]
Imam al-Mubaarakfoori rahimahullah said:
“O seeker of evil stop: that is, oh the one who wants disobedience, hold back from your disobedience and return to Allah because this is the time of the acceptance of repentance and the time to prepare for forgiveness. It is possible that the obedience of the obedient, repentance of the sinner, and the return of the deficient ones in Ramadan is from the effects of the two calls and the result of Allah turning towards those seeking. Like this, we see most of the Muslims fasting, even the children and the neighborhood. Rather, the majority of those who abandoned prayer become then praying people. Although [the case is, is that] fasting is harder than prayer and it creates the weakness of the body which leads to laziness in worship and a lot of sleep usually. Along with this, you see the masaajid full and the revived nights flooded. And all praise is due to Allah and there is no strength or might except with Allah. This is what was mentioned in Mirqaa.”
[Taken from Tuhfatul Ahwaadhi]
Faisal Ibn Abdul Qaadir Ibn Hassan