He is the most pure one, devoid of all blemish, shortcoming, weakness, heedlessness and error.
Al-Quddus is the equivalent of the attribute mukhalafatun lil-hawadith - He is the Creator "bearing no resemblance to the created." This is one of the five qualities that indicate the non-resemblance of Allah to anything.
Al-Quddus is the unique purity that is Allah's, whereby His essence, His attributes, His names, His words, His actions, His justice, are devoid of all blemish. He bears no resemblance, in any of His attributes or actions, to even the most perfect of His creatures. Even the most perfect creatures have something lacking in their essence, attributes, actions, judgments, or words. For one thing, they are temporal, while Allah - the most perfect, the most pure, is eternal, free of time and place. Before existence there was no time and no place, but Allah existed.
The believers who understand and feel this divine purity will wish to praise Allah for His perfection (taqdis) and will remember to avoid attributing any qualities that are defective or any temporal imperfect state to Allah (tasbih).
To find the feeling of al-Quddus in oneself, one should work on cleansing one's faith by eliminating doubts. Faith is a whole. The existence of a single doubt blemishes it. One should try to cleanse one's devotions and prayers by sincerity. Sincerity in prayer is to pray to Allah for Allah's sake, for no other purpose, seeking no other benefit. Otherwise the prayer itself becomes shirk, the unforgivable sin of associating equals with Allah. One should try to cleanse one's heart by abandoning bad habits; bad habits are like garbage and thorns, and our hearts are Allah's houses. He says, "I do not fit in heavens and earth, but I fit into the hearts of My believing servants."
'Abd al-Quddus is he whose heart is cleansed and purified, and contains none but Allah. A heart filled with Allah is safe from all but Him entering it. The manifestation of the name Ya Quddus, the Most Pure, could only appear in a heart described by Allah in the Holy Tradition: "I do not fit into the heavens and the earth, but I fit within the heart of my faithful servant."1
AL-QUDDUS - The Most Holy One
Al-Quddus is the one who is above every description which human perception could apprehend, the imagination could grasp, the fancy could reach, the innermost consciousness could pervade and thereby have an understanding of Him, or the reflection could determine. I do not merely say that He is free of faults and deficiencies, for the mention of this would be akin to a breach of propriety. Certainly it is not part of propriety for one to speak of the king of a country and say, "He is not a weaver," or "He is not a cupper." For to deny the existence of an object in one sense of the word almost suggests that this object may exist and together with that suggestion there is a deficiency.
I would rather say that the Most Holy One is totally free from all of the characteristics of perfection as the majority of people commonly understand this concept. This is the case since man normally looks to himself, first of all, in order to become acquainted with his own characteristics and thereby realizes that only some of them are perfect. The perfection he sees is related to his knowlege, power, hearing, seeing, speech, will and choice: In conjunction with these faculties he applies the term, saying that these are the names of perfection.
But this self-inspection also reveals areas of imperfection in respect of his ignorance, incapacity, blindness, deafness and dumbness, and vis-a-vis these faculties he applies the term imperfections. The aim of his praise and characterization of God Most High is that he might portray Him in terms of the qualities of his own perfection, such as his knowledge, power, hearing, sight and speech as though at the same time he withholds from Him the characteristics of his imperfections.
But God Most High is completely free from characterizations in terms of man's perfection, even as He is free from characterization in terms of man's imperfections. God Most High is free from and exalted above every attribute that one could possibly ascribe to man, and above everything resembling them. Unless there is special permission to use (names) and it is proper (to do so), the majority of these attributes cannot be ascribed to God Most High. But you already understand this subject from the fourth section of the introduction, and therefore it is not necessary to repeat it here.
An Admonition: Man is holy to the extent that he sublimates his will and knowledge. As far as his knowledge is concerned, he should sublimate it from all objects of imagination, from things perceived through the senses as well as those merely fancied, and from all those perceptions in which the animal kingdom shares. Rather the activities of his reflection and his knowledge should be concerned with those things which are above being (either) near and apprehensible by sense, or distant and inaccessible to sense. In fact, he must rid his inner being of all objects-of-sense perception and imagination and must acquire such forms of knowledge that, even were he deprived of the instruments of his sense perception and his imagination, it would continue to be noble, universal, divine knowledge related to the eternal and everlasting objects-of-knowledge, not personal (knowledge) subject to change and alteration.
As far as his will is concerned, he should keep it free from concern for human fortunes which in the final analysis are reduced to the pleasures of passion, anger, eating, marrying, dressing, feeling and gazing upon things, and the remainder of the pleasures he may attain by means of his sensory perception and the desires of his heart. Rather will he desire God alone. He will find pleasure only in God. His only real desire will be his meeting with God, and he will rejoice only in his proximity to God. If Paradise and all its delights were offered to him, he would not concern himself with them. He will not be satisfied with anything in the house except the Lord of the house Himself.
In short, the sensory and imaginative perceptions are shared by the animal kingdom. This being the case, it is imperative that he advance beyond them to those things which are the particular characteristics of man. Appetitive, human satisfactions the animal kingdom knows also. Therefore, it is necessary that he free himself from these. The dignity of the seeker is commensurate with the dignity of that which he seeks. The one whose concern is with that which enters the belly will discover that his value is found in that which goes out of it. But the one who has no aspiration at all except for God Himself, will have a rank commensurate with his aspiration. The one who raises his knowledge above the stage of mere sensory perceptions and imaginations and dedicates his will to that which is above the demands of appetite, certainly he has entered the fullness of the realm of holiness.2