أسباب إجابة الدعاء وموانعه
Abu Umāmah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) was asked: "Which supplication is most likely to be answered?" He said: "A supplication made in the middle of the last part of the night and after conclusion of the obligatory prayers."
عن أبي أمامة -رضي الله عنه- مرفوعاً: قيل لرسول الله -صلى الله عليه وسلم-: أيُّ الدعاء أسمع؟ قال: «جَوْفَ الليل الآخِر، ودُبُر الصلوات المكتوبات».
شرح الحديث :
The Prophet (may Allah's peace and blessings be upon him) was asked about the supplication that is more expected to be answered. He replied that it is the supplication made during the last part of the night and the supplication made at the conclusion of the obligatory prayers, i.e. before making Taslīm. This is supported by the fact that Allah ordained Dhikr to be said after the prayer is over, whereas the Prophet (may Allah's peace and blessings be upon him) ordained supplication to be said between Tashahhud and Taslīm. Making supplications after the prayer is over on a regular basis is not an act of Sunnah; it is considered innovation in religion. This is because making supplication regularly before or after the post-prayer Adhkār renders them a regular act of Sunnah. There is no harm on the Muslim to do it occasionally although it is preferable to give it up altogether. Allah, the Almighty, ordained Dhikr only to be said after prayer, as He said: {And when you have completed the prayer, remember Allah} [Sūrat An-Nisā': 103] Also, the Prophet (may Allah's peace and blessings be upon him) did not instruct us to make supplications after prayer; rather, he urged us to make supplications after Tashahhud and before Taslīm. This is what is confirmed by the texts and accepted by reason since the praying person supplicates to his Lord while he is communicating with Him during the prayer and before leaving it.