The sign that thou lovest God, is this, that thou lovest thy fellow; and if thou hatest thy fellow, thy hatred is towards God. For it is blasphemy if thou prayest before God while thou art wroth. For thy heart also convicts thee, that in vain thou multipliest words: thy conscience rightly judges that in thy prayers thou profitest nought.
-St. Ephraim the Syrian, ON ADMONITION AND REPENTANCE.

Wherefore then doth Christ thus reply to him, saying, "There is none good?" Because He came unto Him as a mere man, and one of the common sort, and a Jewish teacher; for this cause then as a man He discourses with him. And indeed in many instances He replies to the secret thoughts of them that come unto Him.
-St. John Chrysostom, Homily 63 on Matthew 19, 4th Century


Rise from love of the world and love of pleasure. Put care aside, strip your mind, refuse your body. Prayer, after all, is a turning away from the world, visible and invisible. What have I in heaven? Nothing except simply to cling always to You in undistracted prayer. Wealth pleases some, glory others, possessions others, but what I want is to cling to God and to put the hopes of my dispassion in Him (cf. Ps. 72:25, 28).
-St. John Climacus, Ladder of Divine Ascent, Step 28: On Prayer; Paulist Press pg. 277, 6th century


Spiritual delight is not enjoyment found in things that exists outside the soul.
-St. Isaac of Syria, Unknown, 7th century


'But I say to you,' the Lord says, 'love your enemies; do good to those who hate you, pray for those who persecute you.' Why did he command these things? So that he might free you from hatred, sadness, anger and grudges, and might grant you the greatest possession of all, perfect love, which is impossible to possess except by the one you loves all equally in imitation of God.
-St. Maximos the Confessor, Unknown, 7th century