Hisn al-Muslim
Repentance and seeking forgiveness — Du'a 4
وَقَالَ صلى الله عليه وسلم: ((أَقرَبُ مَا يَكُونُ الرَّبُّ مِنَ العَبدِ فِي جَوفِ اللَّيلِ الآخِرِ فَإِنِ استَطَعتَ أَن تَكُونَ مِمَّن يَذكُرُ اللَّهَ فِي تِلكَ السَّاعَةِ فَكُن)).
English meaning
He said: ‘The nearest the Lord comes to His servant is in the middle of the night, so if you are able to be of those who remember Allah at that time, then be so.