If you ask a person to make du'a for you, and he is one whose response is expected, your intention in doing so should be for his benefit, not for your own benefit.

The Shaykh : However, you should note that if you ask a person to make du'a for you, and he is one whose response is expected, your intention in doing so should be for his benefit, not for your own benefit. If you ask a person whose response to du'a is expected to make du'a for you, your intention in asking him should be for his benefit, not for your own benefit. How can it be for his benefit? Yes, because when a person makes du'a for his brother in his absence, the angel says, "Ameen, and for you the same." So if your brother, whom you asked to make du'a for you, makes du'a for you in his absence, the angel says, "Ameen, and for you the same." But if you ask him to make du'a for you and you want nothing but your own benefit, then this is feared to be of the blameworthy asking, because among the things the Prophet (peace and blessings be upon him) took a pledge from the people not to do was asking people for anything. This asking occurs frequently among people; they say, "Make du'a to Allah for me." I am not saying do not say, "Make du'a to Allah for me," but be aware that you want his benefit through this, and consequently your own benefit. This is a matter we should be alert to so that we do not fall into the blameworthiness of this asking.