Ibn Hajar explains: “A group of Sufis used this report as evidence to support the permissibility of singing and listening to songs, whether accompanied by musical instruments or not.
It suffices as a response that `A’isha herself clarified the words of the report by saying, ‘they were not singers,’ negating what could be interpreted from the first part of her report , because ghina’ [singing] refers to raising the voice, the melody which the Arabs call nasb, and the chanting of the caravan leader. The performer of this act is not called a mughanni [singer], which is a term that refers to those who sing by elongating and breaking the words, stimulating and provoking the listener by way of allusive and explicit descriptions of indecency.
Qurtubi says, ‘The statement of `A’isha – they were not singers – means that they were not of those who are experts at singing like professional singers. This is an indication by `A’isha (may Allah be pleased with her) of her wariness and reservation from the customary form of singing, which moves the motionless, and arouses what is deeply hidden. This is a type of singing whose impermissibility is agreed upon, if it consists of poetry that depicts the attractive features of women, intoxicants, and other forbidden things.’
He continues, ‘As for what the Sufis have innovated in this regard, then it is impermissible without disagreement. However, a large number of those attributed with virtue have been overcome by their appetitive souls, to the extent that many of them have displayed acts that are normally associated with children or the insane, such as dancing with organized steps and synchronized movements. Some of them even have the audacity to deem these acts as righteous deeds and a means of seeking nearness to God. They claim that these acts help to attain exalted states, while in reality they are among the indicators of zandiqa [heresy] and the statements of magicians. And Allah is the source of all help!’
In fact, the truth is the reverse of what they say: these acts help to attain the most evil of states.”
Ibn Hajar, Fath al-Bari, 442 [ as cites in "Prohibited Forms of Dhikr by Shaykh Abdul Fattah Abu Ghuddah" ]
Do not confuse with Sufism or Tasawwuf. Sufism/Tasawwuf is a branch of Islamic knowledge which focuses on the spiritual development of the Muslim.