Jami` at-Tirmidhi 3598

Abu Hurairah narrated that the Messenger of Allah (ﷺ) said:“There are three whose supplication is not rejected: The fasting person when he breaks his fast, the just leader, and the supplication of the oppressed person; Allah raises it up above the clouds and opens the gates of heaven to it. And the Lord says: ‘By My might, I shall surely aid you, even if it should be after a while.’”