There are many times and places where du’aa’ is answered. There follows a summary thereof:
1 – Laylat al-Qadar. It was narrated that ‘Aa’ishah asked the Prophet (peace and blessings of Allaah be upon him): “If I know what night is Laylat al-Qadar, what should I say during it?” He said: “Say: Allaahumma innaka ‘afuwwan tuhibb ul-‘afwa fa’fu ‘anni (O Allaah, You are forgiving and love forgiveness, so forgive me).”
2 – Du’aa’ in the depths of the night, the time before dawn, the time when Allaah descends to bestow His bounty upon His slaves, to meet their needs and to relieve their distress, when He says: “Who will call upon Me, that I may answer Him? Who will ask of Me, that I may give him? Who will seek My forgiveness, that I may forgive him?” narrated by al-Bukhaari, 1145.
3 – Following the prescribed prayers. According to the hadeeth of Abu Umaamah, it was said: “O Messenger of Allaah, which du’aa’ is heard?” He said: “In the last third of the night, and following the prescribed prayers.” Narrated by al-Tirmidhi, 3499; classed as hasan by al-Albaani in Saheeh al-Tirmidhi.
There was some difference of scholarly opinion concerning the phrase dabr al-salawaat al-maktoobah (“following the prescribed prayers”) – does it mean before the salaam or afterwards?
Shaykh al-Islam Ibn Taymiyah and his student Ibn al-Qayyim were of the view that it is before the salaam. Ibn Taymiyah said: “The word dabr refers to something that is part of a thing, like dabr al-haywaan (the hindquarters of an animal).” Zaad al-Ma’aad, 1.305.
Shaykh Ibn ‘Uthaymeen said: “What has been narrated of du’aa’ following the prayer is before the salaam and what has been narrated of dhikr following the prayer is after the salaam, because Allaah says (interpretation of the meaning):
“When you have finished As-Salaah (the congregational prayer), remember Allaah standing, sitting down, and (lying down) on your sides”
[al-Nisa’ 4:103]
See: Kitaab al-Du’aa’ by Shaykh Muhammad al-Hamad, p. 54
4 – Between the adhaan and the iqaamah. It is narrated in a saheeh report that the Prophet (peace and blessings of Allaah be upon him) said: “A du’aa’ offered between the adhaan and iqaamah is not rejected.” Narrated by Abu Dawood (521) and al-Tirmidhi (212). See also Saheeh al-Jaami’, 2408.
5 – When the call for the prescribed prayers is given and when the ranks are drawn up for battle, as it says in the marfoo’ hadeeth of Sahl ibn Sa’d: “There are two that will not be rejected, or will rarely be rejected: du’aa’ at the time of the call for prayer and at the time of battle when the fighting begins.” Narrated by Abu Dawood; it is a saheeh report. See Saheeh al-Jaami’, 3079.