This article makes a general research in the specific features of Shia’s kalam (speculative theology) in irfan’s (Islamic mysticism) views of Ali ibn Inayatullah Bastami, known by the nick-name Bayazid Thani (the Second), especially in his book Rawzat al-arifin. The author has been an arif (mystic) and muhaddith (erudite in Prophet’s traditions) who has lived in X-XI century from Hijra. His purpose for writing this tractate has been to clarify some aspects of monotheism, faith, irfan and the principles of the mystical Way. The article is an effort to give an answer to the following questions: first, how the author as a  sufi, in the perspective of Oneness of Existence, and a Shia’s muhaddith can explore the topics of Twelve Shia’s theology within the paradigm of irfan and deepen in this domain; second, is it convenient and acceptable to the mystical wisdom or not, as a principle, that a sufi can use kalam’s proofs and demonstrations, knowing the negative mystical attitude toward rational discussions and issues of kalam.

After considering the most important features of Shia’s kalam in the book Rawzat al-arifin and comparing them with the kalam’s themes, examined by the greatest Shia’s mutakallimun before the time of our author, we could make the conclusion that he has been Shia’s mutakallim and arif in the same time, dwelling on irfan to make an explanation of kalam’ s subtleties. And it could be said also that as his irfan is demonstrative (kalami), his kalam is mystical (irfani).