As-Salaam alaikum,
Sayyadi Darani (d. 830) was expelled from Syria for declaring he had a vision of the angels in which he was also spoken to by them. Sayyadi Abu Yazid al-Bistami (d. 874/5) was driven out of his hometown for claiming to have undergone a heavenly ascent (Mi'eraj) similar in kind to that of the Prophet of Islam, Sallallahu alaihi Wasallam.

As noted by Sayyadi Abu Hamid al-Ghazali, the Prophet, Sallallahu alaihi Wasallam, possessed 2 kinds of knowledge: One which he gave freely to the common lot of believers, and the other which he revealed only to select group of companions. The implication, of course, is that the latter was mystical or esoteric in nature.

This was why Abu Hurairah, may Allah be pleased with him, was quoted saying, "I have preserved from the Messenger of Allah-alaihi-s-Salaam- 2 vessels (of knowledge), one from which I have freely given you, but were I to disseminate (what is in) the other, this throat would be cut off (laquti'a hazal-hulqum)"... and also Sayyadi Hudhayfa Ibn al-Yamani, may Allah be pleased with him, (d. 657) was another companion to whom the Prophet revealed not only the identities of the hypocrites, but more importantly, "the mysteries of knowledge (Sara' iral-ilm), subtleties of understanding (daqa'iq al-fahm), and secrets of certainty (khafayal-yaqin)."

You may wish to refer to Abu Hamid al-Ghazali's
"IHYA ULUM AL-DIN (Revival of Religious Sciences in Islam)",
for more on this matter..