Answered by Shaykh Amjad Rasheed
We often hear from our Sufi brothers that the spirits of the saints (Ar. awliya’) attend their gatherings. Some even go so far as to claim that the Messenger of Allah (Allah bless him and grant him peace) attends with them. What is the ruling regarding this belief: is it prohibited, permissible, or obligatory to believe in? I know that it’s logically possible for spirits to attend gatherings of dhikr, but is there any textual evidence to support this claim? And do the spirits of the deceased leave their graves and roam the earth?
In the Name of Allah, Most Merciful and Compassionate
May His blessings and peace be on His Beloved Prophet, the best of creation, and his family, companions, and followers
What the questioner (Allah preserve him) is asking about is logically and legally possible because it falls under the rubric of [m: belief in] the marvels (Ar. karamat) of saints, which is well-established with Ahlus-Sunnah wa Al-Jama`ah. A marvel is a preternatural phenomenon that Allah manifests at the hands of a saint. The relied-upon position with our imams, Ahlus-Sunnah, is that whatever can occur as a miracle (Ar. mu`jizah) at the hands of a prophet can [m: also] occur as a marvel (Ar. karamah) at the hands of a saint because both are preternatural phenomena and are empirically possible.  The only difference is that if this preternatural phenomenon appears at the hands of a prophet who has been challenged, it is called a miracle and if it appears at the hands of a saint, it is called a marvel. The proofs for the logical and legal validity of marvels are too lengthy to mention. The imam, Sheikh Al-Islam Taj Al-Deen Al-Subki Al-Shafi’i has excelled in putting forth these proofs and rebutting against those who deny them from the Mu’tazila. This is found in his magnificent book, Al-Tabaqat Al-Kubra, which anyone interested can review. Imam Al-Nawawi mentions some of these [m: proofs] in his Bustan Al-`Arifeen, as have many others.
Given that the possibility of marvels occurring is logically and legally established, it isn’t thereafter necessary to request proof for each individual instance. As long as the person who claims it and reports it about himself is one whose religion is upright and what he claims isn’t logically or legally impossible, it is forbidden to accuse him of lying because of the harm and unsupported accusation this entails, which is forbidden.
Regarding the ruling of believing in such issues: as was mentioned, this falls under the rubric of the establishment of [m: the belief in] marvels. It is obligatory to believe that marvels can occur at the hands of saints because of the proof that supports it. [m: The author of] the Jawharah  says:
Marvels to saints, these you must impute;
Who denies this, his words you refute!
The commentator [m: on the Jawharah], the erudite scholar, Sheikh Abdul-Salam Al-Laqani says (p. 128):
The author’s intent is that is it obligatory for every legally responsible person (Ar. mukallaf) to believe in marvels, i.e. that they are real, meaning that they are possible and occur at the hands [m: of saints], as is the position of the majority of Ahlus-Sunnah.
– Amjad Rasheed
(Translated by Sidi Moustafa Elqabbany)
 The literal meaning of mu`jizah is something that incapacitates its opponents. The literal meaning of karamah is a token of honour. In this article, mu`jizah is translated as “miracle” while karamah is translated as “marvel”.
 Jawharah Al-Tawheed is a canonical versification of Ash’ari creed and is a standard part of traditional Islamic curricula.]