Abu Umamah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) was asked: "At what time does the supplication find the greatest response?" He (ﷺ) replied, "A supplication made during the middle of the last part of the night and after the conclusion of the obligatory prayers."[At-Tirmidhi].
App reference: Book 17, Hadith 36
Arabic/English book reference: Book 17, Hadith 1500