Imam Abul Hasan al-Hadi (a.s.), in his talk with al-Fat~h bin Yazeed al-Jirjani, declared the impossibility of describing the Wise Creator with any attribute that might cover his essence and truth. He said, ‘The Creator is not described except with that which He Himself had described Himself with. How can the Creator, Whom senses fail to conceive, minds to arrive at, imaginations to contain, and sights to surround, be described? Exalted is He above what describers say, and glorified is He above what depicters prescribe. He is far in His nearness, and near in His farness. He has adapted the “how” that it is not said (for Him) how, and has adapted the “where” that it is not said (for Him) where. He is out of how and where. He is Only, One, Eternal, Absolute. He begetteth not, nor was begotten, and there is none comparable unto Him. Glory be to Him. Or how is Muhammad (blessings be on him and on his progeny) described in his essence where Allah the Sublime compared him with His own name, participated him in His gift, and promised whoever obeyed him to be rewarded for his obedience when He said, (and they did not find fault except because Allah and His Messenger enriched them out of His grace)? It tells the saying of those who give up His obedience and He tortures them between the covers of Hellfire and its garments of tar, (O would that we had obeyed Allah and obeyed the Messenger). Or how are those (the Ahlul Bayt), whom Allah the Sublime compared their obedience with the obedience of His messenger, described in their essence when He said, (O you who believe! obey Allah and obey the Messenger and those in authority from among you), and(and if they had referred it to the Messenger and to those in authority among them), and, (Surely Allah commands you to make over trusts to their owners), and, (so ask the followers of the reminder if you do not know)?
O Fat~h, as Allah, glory be to Him, the messenger, the guardian (imam Ali), and the sons of Fatima (the infallible imams) can not be described, neither can a believer who believes and submits to our matter be.’( Kashf al-Ghummah, vol.3 p.176.)
Reference : The Life of Imam ALI bin Muhammad AL-HADI