There are three supplications that will undoubtedly be answered: the supplication of the oppressed

There are three types of supplications that Allah will answer without a doubt. They are the supplication of one who has been wronged, even if the person who has been wronged is a disbeliever and was oppressed. If he supplicates to Allah, Allah will answer his supplication. The second is the supplication of a traveler, if he supplicates to Allah, the Exalted, during his journey. The third one is the supplication of a parent – a father or mother – whether for or against their child.