Muwatta Malik 689

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عَمِّهِ أَبِي سُهَيْلِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّهُ قَالَ إِذَا دَخَلَ رَمَضَانُ فُتِّحَتْ أَبْوَابُ الْجَنَّةِ وَغُلِّقَتْ أَبْوَابُ النَّارِ وَصُفِّدَتِ الشَّيَاطِينُ ‏.‏

Yahya related to me from Malik from his paternal uncle Abu Suhayl ibn Malik from his father that Abu Hurayra said, "When Ramadan comes the gates of the Garden are opened and the gates of the Fire are locked, and the shayatin are chained

Reference

Muwatta Malik 689

In-book

Book 18, Hadith 5