By the 9th century AD, the teachings of Harith-ibn-i Asad al-Muhasibi (founder of the important doctrine of self examination) on love and pantheism, along with the teachings of Dhu-l-Nun of Egypt (a legendary half mystic/half alchemist, master of hieroglyphics and hermetic wisdom) led to the development of pantheism in Tasawuf. Muhasibi, in his treatise on love carefully presents his conception of union while Dhul-Nun alludes to pantheism in a covert manner. It was some years later that Abu-Yazid-al-Bastami, known as Bayazid, the first of the intoxicated sufis, was transported upon the wings of mystical fervour. He found God within his own soul and scandalised the orthodoxy, crying: "Glory to me! How great is my majesty!" The utterances of Bayazid created great problems for the sufis who were repressed and persecuted by the religious orthodoxy to such an extent that they were forced to reinterpret them as innocent blasphemy. Bayazid, however, explained the secret of his troublesome utterances as: "It is God that speaks with my tongue, and I myself have vanished." Bayazid describes his mystical experience as follows:
"I saw that my spirit was borne to the heavens. It looked at nothing and gave no heed, though paradise and hell were displayed to it, for it was freed of phenomena and veils. Then I became a bird whose body was oneness and whose wings were of everlastingness, and I continued to fly in the air of the absolute until I passed into the sphere of purification and gazed upon the field of eternity and beheld there the tree of oneness. When I looked, I myself was all those. I cried, 'Oh Lord, with my egotism I cannot attain to thee and I cannot escape from my selfhood. What am I to do?' God spake, 'Oh Abu Yazid, thou must win release from thy thouness by following my Beloved (Mohammad). Smear thine eyes with the dust of his feet and follow him continually." (Kashf-ul Mahjub)
The following narrative is attributed to Bayazid.
"Once he raised me up and stationed me before him, and said to me: 'Oh Abu Yazid, truly my creation desires to see thee.' I said: 'Adorn me in thy unity, and clothe me in thy selfhood, and raise me up to thy oneness so that when thy creation see me they will say: 'We have seen thee, and thou wilt be that and I shall not be there at all."
The tenth century produced a great number of masters and the most notable among them was al-Hallaj, the greatest of the intoxicated sufis. Hussein-ibn-i Mansur-al-Hallaj was a wool carder of Magus origin. After wandering for a long time in different countries, especially in India, he returned to Baghdad and began to teach Tasawuf. He was a contemporary of the famous al-Junaid but younger than him. He agreed with al-Junaid that the supreme mystical experience is a reunion with God, but he proceeded further to teach that man is by nature God incarnate, taking as example, Jesus of Nazareth. He never claimed divinity for himself but his famous utterance was:
"In my garment there is no one except Allah I am the supreme reality." (Ana-l-Haqq)
This phrase which is equivalent to Soham or Aham Brahma Asami shows how closely the Sufi and tantric traditions coincide. Swami Sivananda of Rishikesh has called al-Hallaj a Sufi brahma jnani'. In 'Kitab-al-Tawasin', al-Hallaj says:
"If you do not recognise God, at least recognise his signs. I am that sign, I am the creative truth, because through the truth, I am the truth eternally. My friends and teachers are Iblis (Satan) and Pharaoh. Iblis was threatened with hell fire yet he did not recant. Pharaoh was drowned in the sea yet he did not recant, for he would not acknowledge anything between him and God. And I, though I am killed and crucified, and though my hands and feet are cut off, I do not recant."
Al-Hallaj was accused of being a heretic by the Caliph al-Mugtadir and his hierarchy in 922AD. When he was in his prison cell, a dervish (equivalent to a wandering sadhu of India) was passing and asked him, 'What is love?' Mansur answered, 'You will see today, you will see tomorrow, and you will see the day after tomorrow.' That day he was tortured, the next day he was crucified and the day after that his body was burnt. When he was tortured, the drops of blood falling on the earth wrote Ana-l-Haqq; after he was burnt, the ash was thrown into the river Tigris still writing Ana-l-Haqq on the water.
Before Mansur was crucified, the people passed throwing stones at him, but he smiled kindly at them. Shibli, a great master of asceticism and devotion also passed and threw a little flower at him. Hallaj cried out to him, 'They are not aware of what they do, but you are. Your flower is harder than their stones for me.'
It seems that Hallaj's death was also acceptable to al-Junaid for, as he told his surprised disciples: 'This man broadcasts the secrets.'
"Who has been initiated into the secrets of Haqq His mouth was sealed and sewed." (Rumi)
In 'Legacy of Islam' R.A. Nicholson describes the crucifixion of Hallaj as follows:
"When he was brought to be crucified and saw the cross and nails, he turned to the people and uttered a prayer, ending with the words, "And these thy servants who are gathered to slay me, in zeal for thy religion and in desire to win thy favour, forgive them, O Lord, and have mercy upon them, for verily if thou hadst revealed to them which thou hast revealed to me, they would not have done what they have done, and if thou hadst hidden from me that which thou hast hidden from them, I should not have suffered this tribulation. Glory to thee in all thou wiliest."