Le parler en langues : est-ce haram ?

Islam's relationship to the question is definitional rather than experiential: the tradition has a closed canon of revelation. Muhammad is 'the seal of the prophets' (33:40), the religion 'perfected' (5:3), and subsequent claims to prophetic revelation are impossible — the theological category (claiming new revelation) is worse than eccentric; historically, claimants have founded movements Islam counts as outside the fold. Glossolalia as claimed-speech-from-God therefore cannot be validated; as private, non-propositional vocalization it is simply foreign to Islamic worship forms, which are textual, bodily, and disciplined. What Islam does have: ecstatic spirituality in Sufism — the dhikr ceremonies (repetition of the divine names) can carry experienced practitioners into absorbed states (hal), and some orders' whirling and vocalizing resemble other traditions' ecstatic worship; jurists debate the legitimacy of induced states, with the classical majority wary and the orders defending them as tasting (dhawq) rather than revelation. The standard Islamic test for any spiritual claim is Shar'ia conformity: does it match the Book and Sunnah? — a test ecstatic utterance cannot pass, and Muslims are counseled to anchor devotion in the commanded forms.