Riyad as-Salihin, Book 17, Hadith 1500 (In-Book) ⓘ
Abu Umamah (May Allah be pleased with him) reported: The Messenger of Allah was asked: "At what time does the supplication find the greatest response?" He replied, "A supplication made during the middle of the last part of the night and after the conclusion of the obligatory prayers."[At-Tirmidhi].
وعن أبي أمامة رضي الله عنه قال: قيل لرسول الله صلى الله عليه وسلم: أي الدعاء أسمع؟ قال: "جوف الليل الآخر ودبر الصلوات المكتوبات" . رواه الترمذي وقال حديث حسن.