Mohsin Fani was a noted 17th century Persian historian from what is now Iran.
[1][2] Some suggest he is the author of Dabistan-E-Mazahib.
Born around 1615 in Iran,[2] Mohsin Fani was once migrated to India, for the study of the religions there, in the time of the sixth Sikh guru, Guru Hargobind Sahib[1] with whom he had friendly relationships.
[2] Bhai Kahn Singh Nabha gave some references to him and his (Fani's) book Dabistan-E-Mazahib to claim his point on Sikhs not following Hindu rituals in Ham Hindu Nahin.
[1]