Why is it necessary to pray at home, and to attend divine service at church? Well, why is it necessary for you to eat and drink, to take exercise, or to work, every day? In order to support the life of the body and strengthen it. So also it is absolutely necessary to pray in order to support the life of the soul, to strengthen the soul, which is sick with sin, and to cleanse it, just as you employ some kinds of food and drink to cleanse your body. If you do not pray, you have inadvisably and most unwisely, supporting, gratifying and strengthening your body in every way, but neglecting your soul.
-St. John of Kronstadt Twentieth Century


"Then Jesus told his disciples a parable to show them that they should always pray and not give up. He said: ‘In a certain town there was a judge who neither feared God nor cared about men. And there was a widow in that town who kept coming to him with the plea, Grant me justice against my adversary. For some time he refused. But finally he said to himself, Even though I don’t fear God or care about men, yet because this widow keeps bothering me, I will see that she gets justice, so that she won’t eventually wear me out with her coming!’ And the Lord said, ‘Listen to what the unjust judge says. And will not God bring about justice for his chosen ones, who cry out to him day and night? Will he keep putting them off? I tell you, he will see that they get justice, and quickly. However, when the Son of Man comes, will he find faith on the earth?’" Luke 18:1-8

Because Jesus had spoken to them of dangers and tribulations, here He provides the remedy for these things, namely, prayer. But not simply any kind of prayer; rather, persistent and attentive prayer. All these tribulations will befall the men of those times, He is saying, but prayer is a great ally, and we must offer prayer persistently and continuously, remembering how the persistence of the widow shamed the judge of unrighteousness. If perseverance softened this man who was full of every wickedness and had no shame before God or man, how much more so shall we move God, the Father of mercy, to take pity, even though He should delay for the present? See that not being ashamed before men is a sign of even greater wickedness. There are many who do not fear God, but who nevertheless are ashamed before men and thus commit less sin. But when a man has no shame even before men, this is the height of wickedness…


-Blessed Theophylact

God does not disregard the prayers of the faithful. Yet He sometimes does not fulfill their desires, only in order to better arrange everything according to His Divine purpose.


-St. Leo of Optina

Perseverance in prayer cleanses the intellect, illumines it, and fills it with the light of truth. The virtues, led by compassion, give the intellect peace and light. The cleansing of the intellect is not a dialectical, discursive and theoretical activity, but an act of grace through experience and is ethical in every respect. The intellect is purified by fasting, vigils, silence, prayer, and other ascetic practices.


-St. Isaac the Syrian