This sincerity is what Sufism or Tasawwuf is, and it is an important - even an essential - science in our religion, it is our ’psychology’, it is about understanding the soul.
Everyone wants the last stage before going through the first two stages.
NB: Sufism, Tasawwuf is a contested term. Sufism is not what you see in many countries in the world today.
Problems with modern Sufis - Sh Hamza Yusuf
Sufism [from Quran & Sunnah] is the practical implementation of Islam.
There is no Tasawwuf except it is in accordance with Quran & Sunnah.
Tasawwuf = Sufism is a knowledge through which one knows the states of the human soul, praiseworthy or blameworthy, how to purify it from the blameworthy and ennoble it by acquiring the praiseworthy qualities, and to journey and proceed to Allah - Most High, fleeing unto Him [by taking a spiritual path - tarîq ].
Sufism is not as people think; merely gathering together to engage in remembrance and recite litanies.
What many are unaware of is that Sufism is a complete and practical method for transforming people from loathsome (i.e. causing hatred or disgust; repulsive) individuals to complete and model human beings.
This is all done through having sound faith, sincere worship, good and correct actions, and virtuous character. ”Many calamities have befallen the Ummah during the last 200 years, but one of the worst has been the rejection of Tasawwuf.”
Sufism is the spirit of the Islamic religion and its quintessential reality and character. It is the pillar of purification, and is expressed as ihsān (excellence) in the rigorously authentic Hadīth report..
The scholars of the Sufis are the genuine followers of the salaf due to the fully connected chains leading back to them. This is the fact of the matter and it is not a mere claim. They are the Muḥammadan inheritors; those in whom Allah has gathered the inheritance of Sacred Knowledge in the inheritance of spiritual states.
The Scholars of the Sufis, They Are the Genuine Followers of the Salaf; Sh 'Abd al-Hadi Kharsa
 "to worship Allah as if you see Him…"
The Gibril - hadith
The science of the religious law (Shariah) has an internal as well as an external aspect and inculcates inward as well as outward actions. The outward actions are bodily, such as hunger, fasting, almsgiving and the like, while the inward actions, or the actions of the heart, are faith, sincerity, knowledge of God, etc.
The esoteric science signifies the science of the actions of the interior which depend on the interior organ, namely, the heart (al-qalb) and is identical with Sufism. The inward aspect of religion is the necessary complement of the outward aspect, and vice versa. Both aspects are inherent in the Quran, in the Traditions of the Prophet ﷺ , and in Islam itself.
Sufism is a science by means of which you learn how to behave in order to be in the presence of the ever-present Lord through purifying your inner being and sweetening it with good actions. The path of Sufism begins as a science, its middle is actions and its end is divine gifts.
Ahmad Ibn ‘Ajiba
The mutasawwif is he that seeks to become a Sufi, bi-idhni-Allah. They are the vast majority, Sufis are the most excelling ones.
The Sufi is he whose language, when he speaks, is the reality of his state.
Sufism is the renunciation of all selfish pleasures.
The Sufi is he that has nothing in his possession nor is himself possessed by anything.
The Sufi is he that sees nothing except God in the two worlds.
As for the would-be-Sufi (mutasawwif) claimants who are nescient of the Sharia or not even concerned by it: they are also heretics and completely undesirable no matter how big they grow their beard, turban, jubba, or voice!
Sh. G F Haddad in The Scholars of the Sufis
The Sufi path consists in cleansing the heart from whatever is other than Allah…
The Sufis are the seekers in Allah's Way, and their conduct is the best conduct, and their way is the best way, and their manners are the most sanctified. They have cleaned their hearts from other than Allah and they have made them as pathways for rivers to run, carrying knowledge of Allah.
Al-Ghazali declared tasawwuf to be a fard 'ayn or personal obligation upon every legally responsible Muslim man and woman, 'as none but Prophets are devoid of internal defects and diseases.'
I accompanied the Sufis and received from them but three words:
□ their statement that time is a sword: if you do not cut it, it cuts you;
□ their statement that if you do not keep your ego busy with truth it will keep you busy with falsehood;
□ their statement that deprivation is immunity.
a knowledge through which one knows the states of the human soul, praiseworthy or blameworthy,
how to purify it from the blameworthy and ennoble it by acquiring the praiseworthy [qualities], and
to journey and proceed to Allah - Most High, fleeing unto Him [by taking a spiritual path - tarīq ].
Religion (al-dîn) is an orchard of which the fence is the Law (al-sharî'a), the inner grove is the Path (al-tarîqa), and the fruit is the Reality (al-haqîqa).
Whoever has no Law has no Religion; whoever has no Path has no Law; and whoever has no Reality has no Path.
O Ali, God is God and men are men. Keep your tongue from the mention of them, and your heart from inclining before them, and be careful to guard the members (jawarih) and to fulfill the divine ordinances; thus the friendship (wilaya) of God is perfected in you. Have no remembrance of them except under obligation that duty to God imposes on you; thus your scrupulousness is perfected. Then say: …
Cafes in Damascus Syria 1830s Samda Kahve
Three fundamental components of our religion:
Allah gave us a religion fit for all these three elements; Islam for the body, faith (Iman) for the mind and excellence (Ihsan)* for the spirit. Hence, a full integration is essential between these three elements so as to have a balanced human being. This balance is the only way to help us (to act correctly) and with this humanity can be set straight. If we become inclined to one element more than the others we instantly fall out of balance.
*Without Ihsan, Iman and Islam there is no tasawwuf.
Excellence is all about Self-Purification
Islam's Universal Values - Sh Hamza Yusuf