15 Mindful then of our condition, that we are essentially limited and absolutely dependent on the Supreme Being, before everything else let us have recourse to prayer. We know through faith how great is the power of humble, trustful, persevering prayer. To no other pious work have ever been attached such ample, such universal, such solemn promises as to prayer: "Ask and it shall be given you, seek and you shall find, knock and it shall be opened to you. For every one that asketh, receiveth; and he that seeketh, findeth; and to him that knocketh, it shall be opened" ( Matth . vii. 7). "Amen, amen I say to you, if you ask the Father anything in my name He will give it you" ( Io . xvi. 23).
Source: Caritate Christi Compulsi (Vatican.va)