Sufism, or Taṣawwuf (الْتَّصَوُّف), variously defined as "Islamic mysticism", "the inward dimension of Islam" or "the phenomenon of mysticism within Islam", is mysticism in Islam, "characterized ... [by particular] values, ritual practices, doctrines and institutions" which began very early in Islamic history and represents "the main manifestation and the most important and central crystallization of" mystical practice in Islam. Practitioners of Sufism have been referred to as "Sufis" (from صُوفِيّ ṣūfiyy / ṣūfī). Historically, Sufis have often belonged to different ṭuruq or "orders" – congregations formed around a grand master referred to as a wali who traces a direct chain of successive teachers back to the Prophet Muhammad.
Our divine leaders are the Prophets and the Infallible Imams and their sincere followers.
We believe that our absolute obedience must be to Allah, the Prophet (SAWA) and the Infallible Ahlul Bayt (AS). Beside them, No saint or scholar etc has the status of absolute obedience on us.
If fact, there is no need at all for saints in Shia Islam as the divine leadership of Ahlul Bayt (AS) is the real leadership for us.
Thank you for your question. If by saints you mean people that have reached closeness to Allah due to their efforts in worship, developing their faith and knowledge, passing trials and tribulations and other such qualities then there is no doubt that Shias not only accept the existence of saints but advocate a path to realize that potential in every person. The most perfect friends of God are the holy Prophet (saw) and his Household (as) as well as the prophets (as) and all of those who follow their footsteps have a place among the friends of God.
May you always be successful and be included among God's chosen friends
It is unlikely that Sufi orders took these practices directly from Imam Ali (A) although they may sometimes ascribe them to Imam Ali (A) as a form of piety. However, it's not unheard of for these things to be done among Shi'i mystics, and in general these practices are found in the mystical traditions in many regions. Maybe they can be viewed more like exercise similar to how if one wishes to strengthen one's muscles, one can lift weights, regardless of one's religious affiliation(s).
You have the freedom to go.
However, if you are a dedicated Shi'i, and are going for reasons beyond casual attendance or academic interest (for instance, seeking long-term spiritual guidance or a sense of belonging), it is unlikely to yield a long-term benefit, because people can tell whether you are one of them or not, and at the end of the day, you will be either one of them or not and share their outlook or not. But it is natural for the seeker to want to look for wisdom in different places.
If you do go, it is good to approach it with a spirit of critical analysis, and sift out what is true, healthy, and founded from what is false, unhealthy, or baseless in what is being said (as well as how the teacher interacts with students and how the group interacts with each other). However this is good for all things, not just Sufi groups.
[Addendum: I agree that, in theory, one should be able to take what one needs spiritually solely through Twelver interpretations of Ahl al-Bayt (A).
However, the reality is that, in many places where Muslims are a minority, there is not much available to Shi'is. Even if there is a Shi'i mosque, it may not be serving the spiritual, educational, or social needs of the people there beyond a basic level. Or the programs may be in a language the person does not speak, etc. One of the main complaints I hear among adult Shi'is is that they feel like their communities do not offer scaffolding for spiritual development because most of the communities are focused on rituals and being cultural centers, and, for this reason, some Shi'is do explore other forms of spirituality or mysticism.
This is in addition to whatever other reasons someone might wish to explore elsewhere, apart from curiosity and the sense that the grass could be greener on the other side (although it usually isn't!).
At the end of the day, we are all Muslims; if you go to a Sunni Sufi class, you will learn more about the diversity and variety of approaches in the Islamic tradition. In my viewpoint, the main difference between Shi'ism and Sunnism is not about Abu Bakr or Umar or how to do wudu but rather worldview - underlying assumptions about the nature of Islam, approaches to religious law, free will, social ideals, etc, of course Sufis vary a lot in these things too, but picking up on the underlying differences is perhaps the most educational thing to do. Also, sometimes when we see a different viewpoint, we come to appreciate our own more!
I don't believe that there is a merit to preserving one's faith only through isolation or ignorance by not exposing one's self to other views. If one's faith can't stand up to the knowledge that there are other approaches, then it doesn't sound like a very strong faith. However, if one is unfamiliar with the foundations of one's religious views, it's good to be solid in them before exploring something different, otherwise you won't be able to compare fairly. For instance, a Muslim came to me once with many criticisms of the Qur'an they read online, however they had never actually read the Qur'an! This is just taking someone's propaganda because one does not know about one's own religion. However if some has a reasonable knowledge of their own faith, it can be rewarding to explore other interpretations of faith and religion, whether they be from other Muslims or other faiths. We are all human beings sharing the same soul and the same general trajectory throughout life to the next life and so there are bound to be some commonalities even if there are also differences. ]
The followers of true Islam which is the Islam of the Holy Prophet
(SAWA) and the Ahlul Bayt (AS) has got the strongest evidence which is not
available with anyone else from any sect from among the Muslims. The
believer ( Mo'min) should share his knowledge and the evidence which he has with
other Muslims who are not aware of it. Attending religious or
scientific gatherings is good as far as the Mo’min gives his knowledge
as much as he can to those who do not follow the Ahlul Bayt (AS). But
attending classes conducted by people who are away from the Ahlul Bayt
(AS) without being able to benefit them is harmful and it must be
avoided. Every believer, no matter how much he knows about religion is
able to give benefit to those who don’t follow Ahlul Bayt (AS). The
Hadeeth from Imam Ja’far Al- Sadiq (AS) says : “If our uneducated
follower does not overcome the educated from our opponent, then we are
not on the right path” (ان لم يغلب جاهلنا عالمهم فلسنا على الحق ).
The believer who knows and follows Ahlul Bayt (AS) does not need to take guidance from outsiders as the Ahlul Bayt (AS) have the most comprehensive and most authentic knowledge from the Holy Prophet (SAWA) which is required by every Muslim.
There is also another negative point in attending religious classes of
other sects which might give a wrong signal to some of them that they
are on the right path and that is why a follower of the Ahlul Bayt
(AS) is seeking knowledge from them.
A narration states : “Seeking religious knowledge from
other that Ahlul Bayt (AS) is like denying the status of Ahlul Bayt
It is not allowed to take part in any practice of Bid'ah.
The Prophet Muhammad (SAWA) and his holy Progeny Ahlul Bayt (AS) practiced remembering Allah (SWT) with out such Halqah, and we must follow them not others.
We respect all our Muslim brothers and their different ways of practicing religion according to their schools of thoughts, but we as followers of Ahlul Bayt (AS), follow the Prophetic way of worshipping Allah (SWT).
Until around the time of Imam al-Sadiq (as), the term 'Sufi' was not in regular use, and the few that used it as an appellation were of the Mu'tazili and Imami schools, not the Sunni Ash'ari or Maturidi schools, which now dominate the Sufi scene.
Sufism is an amalgamation of Islamic ideas and practices and others that have been integrated into it from spiritual traditions that existed prior to Islam expanding into wider territories.
I have written a paper on this in more detail, if you are interested. Please write to me at email@example.com and I can send it to you.
Thank you for your question. Spirituality is an essential aspect of the source literature (which are the bases of the true teachings of Islam), however, the term Sufism remains loosely defined in western scholarship and it has been the subject of much discussion.
The term invokes a specific reading of the history of mysticism, its theology, its institutions and its practices and it can be argued that it is a predominantly Sunni account of spirituality in the Muslim world. Discussion of the sources of this tradition was an important question in the early study of Sufism and while some scholars claimed that the sources of Sufism were outside of the scriptural sources, others argued that they were rooted in them. The second opinion became more acceptable and early Companions of the Prophet (saw) were referred to as proto-Sufis, signifying that the Sufi tradition was a later development, while its sources firmly originated in Islam.
Juxtaposing Shi'i to Sufism (Shi'i Sufism) may adequately describe some Shi'i expressions of Sufism, and indeed the term irfan was used by some seminarians in Iran to distinguish a tradition acceptable to the traditional seminary, different to these forms of Shi'i Sufism. The importance this form of irfan places on the divine law and its inner aspects, as well as in the more complex aspects of tawhid and walayah ensues that it provides a strong reading of the scriptural sources. It has also been argued that the Shi'i source literature has a mystical aspect of its own and is, therefore, the impetus of its own form of spirituality.
May you always be successful.