The first Shia Imam, Ali ibn Abitaleb (AS) narrated from the Prophet of Islam (PBUH) who said:

Dua from four groups is not rejected. The doors of the sky open for them and their invitation reach the Divine Throne (meaning; no obstacle remains for acceptance of Dua). These groups are:

1. Father’s Dua for his children
2. The curse of the oppressed against the oppressor
3. Dua of the person who is performing Umrah until he/she returns home
4. The fasting person’s Dua until the time of Iftar [1]

[1] Osul Kafi, Vol. 3, Page 638.

Source: en.shafaqna.com