Doubt is named doubt because it resembles truth. As for lovers of Allah, their conviction serves them as light and the direction of the right path serves as their guide; while the enemies of Allah, in time of doubt call to misguidance in the darkness of doubt and their guide is blindness. One who fears death cannot escape it nor can one who fears for eternal life secure it.
Imam Ali, Nahjul Balagha – Sermon 38
Praise is due to Allah whose worth cannot be described by speakers, whose bounties cannot be counted by calculators and whose claim (to obedience) cannot be satisfied by those who attempt to do so, whom the height of intellectual courage cannot appreciate, and the divings of understanding cannot reach; He for whose description no limit has been laid down, no eulogy exists, no time is ordained and no duration is fixed. He brought forth creation through His Omnipotence, dispersed winds through His Compassion, and made firm the shaking earth with rocks.
The foremost in religion is the acknowledgement of Him, the perfection of acknowledging Him is to testify Him, the perfection of testifying Him is to believe in His Oneness, the perfection of believing in His Oneness is to regard Him Pure, and the perfection of His purity is to deny Him attributes, because every attribute is a proof that it is different from that to which it is attributed and everything to which something is attributed is different from the attribute. Thus whoever attaches attributes to Allah recognises His like, and who recognises His like regards Him two; and who regards Him two recognises parts for Him; and who recognises parts for Him mistook Him; and who mistook Him pointed at Him; and who pointed at Him admitted limitations for Him; and who admitted limitations for Him numbered Him.
Whoever said in what is He, held that He is contained; and whoever said on what is He held He is not on something else. He is a Being but not through phenomenon of coming into being. He exists but not from non-existence. He is with everything but not in physical nearness. He is different from everything but not in physical separation. He acts but without connotation of movements and instruments. He sees even when there is none to be looked at from among His creation. He is only One, such that there is none with whom He may keep company or whom He may miss in his absence.
Imam Ali, Nahjul Balagha – Sermon 1