ST ISAAC THE SYRIAN - ASCETICAL HOMILIES #5

On Keeping Oneself Removed From the World and From All things That Disquiet the Intellect...page 46

And whenever you are ill say, 'Blessed are those who discover the object which God has placed in what He brings upon us to profit us!  For God administers sicknesses for the health of our soul.  For one of the saints said, 'I have taken note of the following, that a monk who does not serve the Lord in a God-pleasing manner, who does not strive earnestly for his soul's salvation, but remains heedless regarding the exercise of virtues, is most assuredly allowed by God to fall prey to temptations so that he be not idle, and from his excessive idleness lapse into a worse state.'  This indeed is why God inflicts temptations upon the lazy and heedless, that they may be preoccupied with these and not with frivolous things.  This God always does with those who love Him [[ but if He sees that they begin to disregard His works, He sends a great trial upon them ]], that He may chasten them, make them wise, and teach them His will.  And whenever they pray to Him, He does not quickly hearken to them, but waits until they grow weary and have learned in no uncertain manner that these things befell them because of their slothfulness and negligence.  For it is written, 'When ye spread forth your hands unto Me, I will turn Mine eyes from you; and if you multiply your prayer, I will not hearken unto you,'  For even if this was said of others also, nonetheless it is written especially about those who have abandoned the way of the Lord.

But since we say that God is plenteous in mercy, why is it that when amidst temptations we unceasingly knock and pray, we are not heard and He disregards our prayer?  This we are clearly taught by the Prophet when he says, 'The Lord's hand is not little, that it cannot save; nor is He heavy of hearing, that He cannot hear; but our sins have separated us from Him, and our iniquities have turned His face away, that He doth not hearken.  Remember God at all times, and He will remember you whenever you fall into evils.