Du’aa is like a weapon, and a weapon is only
as good as the person who is using it; it is
not merely the matter of how sharp it is. If the
weapon is perfect and free of faults, and the
arm of the person using it is strong, and
there is nothing stopping him, then he can lay
waste the enemy. But if any of these three
features is lacking, then the effect will be
lacking accordingly.
Ibn Qayyim Al Jawziyyah