In the Name of Allah, the Beneficent, the Merciful
Praise be to Allah, the Lord of the worlds, and may Allah send blessing onto Muhammad and his pure progeny, and may His curse be upon all their enemies, from now till the rise of the Day of Judgement.
O Allah! Our steps of travelling are too short to reach Your Sacred Court, and our demanding hand is unable to touch Your Skirt of Intimacy. The veils of desire and negligence have blocked our insight from Your Beautiful Beauty, and the heavy curtains of loving this world and devilry have secluded our hearts from attending to the Glory of Your Majesty. The road to the Hereafter is narrow, and the path of humanity is sharp, while we, the helpless, like the spiders, think of the jerked meat. We, like the silk worms, are perplexed, tying ourselves with the chains of desires and hopes, completely closing our eyes against the unseen world and the sociable gathering, except for the divine brightness with which You may light our hearts, and for Your unseen firebrand with which You may take us into rapture.
O Allah! Grant me to be exclusively dedicated to You. Light the eyes of our hearts with the light of looking at You, until the eyes of the hearts penetrate through the partitions of light so as to reach the origin of greatness, and our souls become hanging onto the glory of Your Sanctity. 
Now then, some years ago, I prepared a paper , in which I inserted as much as was possible of the secrets of the salat. But as it was not suitable for the common people, I decided to write parts of the cordial disciplines of this spiritual mi'raj, so that my brethren in faith may have a remembrance and my hard heart may be affected by it. I take refuge with Allah, the Blessed and Most High, from Satan's conduct and from failure, for He is a powerful guardian. I have arranged in this book a preface, a few discourses and a conclusion.
Know that for the salat, beside its form, there is a meaning, and apart from its exterior it has an interior; and as the exterior has its disciplines, neglecting which would render the outer form of the salat invalid or incomplete, likewise its interior has cordial spiritual disciplines, neglecting which would render the spiritual salat invalid or incomplete; whereas observing them would inspire the salat with a heavenly spirit. It would be possible that after paying attention to and observing the cordial inner disciplines, the musalli would have a share of the divine secret of the salat of the "people of knowledge and of hearts" -the salat which is the delight of the people of suluk  and the reality of the mi'raj (ascension) to the proximity of the Beloved.  Besides what was just said about the salat's interior and unseen divine images, and in addition to its being in conformity with a kind of proof and the observations of the people of suluk and asceticism, there are many ayahs and narratives, in general and particular, which denote that, too, and we shall bless the following pages by relating some of them.
Among them is the saying of Allah, the Most High:
"On the day when every soul shall find present what it has done of good and what it has done of evil, it shall wish that there were a long duration of time between it and that [day] ... ""  This noble ayah says that everybody will see his good and bad deeds present and he will discern their unseen inner images. In another ayah He says: " ... and they shall find present what they have done,"  and: "So, he who has done an atom's weight of good shall see it ... ,"  which means that the soul shall see its deeds.
As regards the noble hadiths in this respect, they are too many to be contained in these pages. So, it suffices to state a few of them.
Among them, in the Wasa'il, quoting Imam as Sadiq (AS), it is said: "Whoever performed the obligatory salats at the beginning of their times and observed their restrictions, the angel would raise them, white and pure, to heaven, and the salat would say (to the performer): "May Allah preserve you as you preserved me and entrusted me to a generous angel'. But whoever performed them after their times, with no excuse, and did not observe their restrictions, the angel would raise them, black and dark, while the salat shouting at the performer:" You have lost me, may Allah lose you, and may He not care for you as you did not care for me'." 
It denotes that the salat is raised by Allah's angels to heaven, white and pure, when it is performed at the start of its time and its disciplines are observed. In this case it invokes good for the musalli; or it will be dark and black if it is delayed, without a reasonable cause, and its disciplines are neglected, in which case it will curse him. This hadith, besides denoting the fact which is heavenly unseen images, it also denotes that they are alive, as evidenced by ayahs and narratives. Allah, the Most High, says: " ... and the next abode, most surely, is the life ...",  There are many hadiths to the same effect, relating which would lengthen the subject.
Imam as-Sadiq (AS) is quoted to have said: "When a believing servant is put into his grave, the salat stands on his right and the zakat on his left, his good deeds stand shadowing over him and forbearance stands aside. When the two angels in charge of interrogation enter the grave, forbearance tells the salat, the zakat and good deeds: 'You are to help your friend. If you felt unable, I would be with him.'  This noble hadith is related in the noble al-Kafi through two channels. Shaykh as-Saduq (may Allah have mercy upon him) has related this hadith in Thawabul A'mal. It speaks clearly of the unseen images of the barzakh, and their life and common sense. The hadiths about the heavenly images of the Qur'an and of the salat are numerous.
With regard to what has been said that the salat and other forms of worship have, besides their outward disciplines, other inward disciplines without which the salat would be incomplete or even unacceptable by Allah, the following pages will numerate and state those cordial (inward) disciplines, insha'allah (if Allah wills).
What one should know, however, in this stage, is that to satisfy oneself with the appearance and outer form of the salat, and to be deprived of its blessings and inner perfections which bring about eternal happiness, or rather, bring one to the proximity of the Lord of Might, and set up the ladder of ascent to the stage of meeting the Absolute Beloved, -the Ultimate Goal of the godly men and the Final Hope of the people of knowledge and those who have "hearts", or rather, the Beloved of the Master of the Messengers (SA).  -is one of the heavier losses, as it will be -after leaving this world and entering the reckoning (day) of Allah -the cause of so great regrets that our minds are incapable of comprehending them. As long as we are enwrapped in the veils of this world, and live in the covers of nature, we cannot have knowledge of the other world, and cannot keep warm by a remote fire. What regret, remorse and loss can be greater than that after forty or fifty years of toiling for the sake of attaining a thing which is the means of man's perfection and happiness, and the remedy for the pains of the cordial deficiencies, and it is, in fact, the image of the human perfection, we cannot be spiritually benefited by it, and rather, it becomes the cause of tarnishing the heart and brings dark veils, and what is the pleasure of the Messenger (SA) causes the weakness of our insight: " ... Alas for me, for what I fell short of my duty to Allah ..." 
So, dear, tuck up the skirt of aspiration, extend the hand of demand, bear every labour and hardship in order to reform your affairs and acquire the spiritual conditions of the salat of the people of knowledge, and make use of this divine mixture [maj'un], which is prepared with the complete understanding [kashf] of Muhammad (SA) for the sake of soothing all the pains and deficiencies of the souls.
Since it is still not too late, try to break camp and leave this dungeon of darkness, regret and remorse, this deep pit that is far away from the holy presence of the Lord, the Exalted and Most High. Release yourself and try to reach the ascension [mi'raj] of union [wisal] and the proximity of perfection.
Beware! if this means was lost, other means would fail: "If it was accepted, other deeds would be accepted, and if it was rejected, other deeds would be rejected, too." 
We shall explain, as much as possible and necessary, the inner disciplines of this spiritual suluk, so that someone of the people of faith may have a share of it. This might as well be a cause for the divine mercy and the unseen care to be bestowed upon me, lagging as I am in the way to happiness and humanity, and chained in the prison of nature and selfishness. Surely Allah is the Patron of generosity and care.
. "Munajat-i Sha'baniyah", Biharul Anwar, vol. 91, p. 99.
. He refers to the book Sirrus' Salat (Mi'rajus-Salikin wa Salatul arifin). The author (may Allah sanctify his honourable tomb, at its beginning, after the praising (Allah), blessing (the Prophet) and invoking, has written: "Now then, I, the bewildered in the valley of perplexity and ignorance, and tied to the wishes of l-ness and egoism, indulged in the intoxicating selfness and egotism, knowing nothing of the spiritual stations and the kingdom of existence, have sincerely decided to write about some of the spiritual stations of the great guardians in this spiritual suluk and mi'raj of faith ..."He has finished the said honourable book on the 21st of Rabi'uth Thani, 1358 L.H. (19 Khurdad, 1318 S.H.).
. It hints at some narratives, including one from the Messenger of Allah (SA) saying that: "My delight has been placed in the salat". Furu' ul Kafi, vol 5, p. 321, "Book of Marriage", ch. on "Loving Women", hadith No.7.
. It refers to a narrative from the Messenger of Allah (SA) saying: "The salat is the mi'raj of the believer", I'tiqadat, by the late 'allamah al-Majlisi, p. 29.
. Surah Al-i' Imran: 30.
. Surah Kahf: 49.
. Surah Zilzal: 7.
. Wasail ush-Shi'ah, vol. 3, p. 90. Kitabus-Salat, chs. on "Times" ch. 3, hadith, 17 (with a slight difference ).
. Surah 'Ankabut: 64.
. 'Usul ul Kafi, vol. 3, p. 143, "Book of Belief and Disbelief', ch. on "Forbearance", hadith, 8. Thawabul A'mal, p. 203. Thawabul-Salat waz-Zakat wal-Birr was-Sabr, hadith, 1.
. Refer to footnote No.7.
. Surah az-Zumar: 56.
. Falahus Sa'il, p. 127, quoting Man la Yahduruhul Faqih, in which the 522 text is: "The first thing about which the servant is questioned is the salat, if it was accepted his other (worshipping) acts would be accepted, and if it was returned to him, his other acts would be returned to him (too)". vol. 1. "The Merit of the Salat", ch. 30, hadith 5.