Bayazid Bastami also known as Abu Yazid Bistami or Tayfur Abu Yazid al-Bustami, (804-874 CE) was a Persian Sufi born in Bostam (alternate spelling: Bastam), Iran. The name Bastami means “from the city of Bastam”. Bayazid Bastami had great influence on Sufi mysticism and is considered to be one of the important early teachers of Sufi Islam.
Bastmi’s predecessor Zu al-Nun al-Misri (d. CE 859) had formulated the doctrine of ma’rifa …(gnosis), presenting a system which helped the murid (initiate) and the shaykh (guide) to communicate. Bayazid Bastami took this another step and emphasized the importance of ecstasy, referred to in his words as drunkenness, a means of union with God. Before him, Sufism was mainly based on piety and obedience and he played a major role in placing the concept of divine love at the core of Sufism.
Bistami was the first to speak openly of “annihilation of the self in God” (fana fi ‘Allah’) and “subsistence through God” (baqa’ bi ‘Allah). His paradoxical sayings gained a wide circulation and soon exerted a captivating influence over the minds of students who aspired to understand the meaning of the wahdat al-wujud, Unity of Being.
When Bayazid died, he was over seventy years old. Before he died, someone asked him his age. He said: I am four years old. For seventy years I was veiled. I got rid of my veils only four years ago.”
He died in 874CE and is buried in the city of Bistam in north central Iran. Bayazid lived a century before Abul Hassan Kharaqani. Attar Neishapouri has mentioned in his book Tazkiratul Awliya that Bayazid had spoken about the personality and state of Shaikh Abul Hassan Kharaqani with his disciples while passing from the village of Kharaqan, almost 100 years before the birth of Shaikh Abul Hassan.
You can read more about him at http://www.aulia-e-hind.com/dargah/Intl/iran.htm#two