Bayazid names a teacher called Abu Ali al-Sindi, from whom, he says, he learned the science of annihilation, and to whom in exchange he taught the obligatory duties of Islam. The name means the man from Sind, in the Indus valley, and that one detail has carried a very large scholarly argument.
The proposal, argued most fully in the middle of the twentieth century, is that the doctrine of annihilation in Bayazid's mouth is not a development of anything already in Islamic ascetic piety but an import: that Vedantic non dualism reached him through this teacher, and that his utterances are recognisably the Upanishadic identification of the self with the absolute in Arabic dress. The parallels adduced are genuine and in places close.
The objections are equally serious. Sind was under Muslim rule and Abu Ali may simply have been a Muslim from that province with no Vedantic training at all; the language of annihilation can be derived from Quranic material without external help; and the argument has been criticised as a case of finding what one already believed was there. No decisive evidence has appeared either way, and the atlas records the question as disputed rather than choosing. It is a good example of a problem in the history of religions that is entirely tractable in principle, and where the surviving evidence is simply too thin to settle it.