Imam Khomeini; Forty Hadith, Twenty Seventh Hadith
‘‘Know that freedom from other work for the sake of absorption in worship is obtainable through:
1. Possessing unoccupied time
2. Possessing an unoccupied heart.
Attentiveness of the heart consists of two matters:
The first of these lies in possessing unoccupied time and an unoccupied heart
The second lies in making one's heart understand the importance of worship.
What is ‘unoccupied time’?
It is that one should set aside a certain time out of his day and night hours exclusively for the sake of worship wherein he should devote himself solely to worship without engaging in any other preoccupation.
If one were to understand that worship is an important thing whose significance is greater than any other activity, or, rather, that it is something of incomparable significance, he would allocate a certain time to it and be careful to observe its timings.
What is ‘unoccupied heart’?
It is that at the time of worship one must disengage himself from mundane engagements and cares and turn his heart away from all kinds of matters and cares and make it entirely empty and unencumbered for attending to worship and supplication with God Almighty.
My dear, consider the prayers you offer to God by comparing them with talk and conversation with one of His insignificant creatures. (a best friend, a spouse, a fiancée, a tutor etc)
When talking to a stranger, you attend to him with all your attention and are oblivious of anyone else as long as you are engaged in conversation with him.
But why is it that while engaging in communication and prayer with your Provider and the Lord and Sustainer of the worlds you are totally heedless of Him and attentive to other matters?
Is the station and worth of creatures greater than that of the Sacred Essence of the Lord?
Is conversation with them more valuable than supplication with the Fulfiller of needs?
Yes, I and you do not know the significance of supplication with God.
We consider these divine duties as a cumbersome burden, and, of course, a matter that is a cumbrous weight on one will not be significant for him.’’