For the Sufi, the most meaningful words in creation are "La ilaha illa 'llah, Muhammadun-Rasulullah." We claim unequivocally that this phrase is the Origin of all Knowledge, the Sun of all Meaning, the Source of all Truth, and Health, Warmth and Healing to the heart.
Let's examine the phrase in its two components, "La ilaha illa 'llah", and "Muhammadun-Rasulullah".
Part 1. La ilaha illa 'llah
"La ilaha illa 'llah" is the essence of the matter, a simple but profound summary of the "Knowledge of God". It is the essence (and practice) of the annihilation of falsehood. It is both a statement of Divine Truth, and a lesson on how to know it. It means that there IS ONLY Allah, and demonstrates that the quickest way to "know" the Unity is to deny all else.
"La" means no, nothing, negating of what follows, indicating the negation of and implying the illusory nature of the seeming existence of whatever it is referring to, (which, paradoxically, must first "exist" (in the mind) in order to be negated, denied, refused, diminished to zero relative significance).
"Ilaha" is an intensely interesting word, worthy of deep consideration. It means god (little 'g' intended), deity, worthy of worship, deification, edification, respect, subordination, following, service, attendance, consideration. In a word, just about anything that comes from our (individual) minds (mindset, way of thinking), and anything we might care about (our cares), or believe "exists".
"La ilaha" can therefore mean "nothing exists", i. e. nothing is worthy of consideration except that which stands by itself and is not in need of consideration. And how do we isolate that Being? By eliminating from our consciousness (mind) all that can be eliminated, even and including all mental concepts (of God), until there is only pure existence itself, pulsing through our bodies and flowing through our veins.
The indication is that the "Knowing" of God is based on the negation of all else. In practice, that negation is based on an exclusive affirmation of The Only Possible Permanent Reality, God Alone. Once the "Knowing" is known, it stands alone and sufficient. There is no more negation necessary or even possible, and everything becomes an affirmation of the Truth in Reality.
In Sufism, the word "annihilation" refers to the mind (giving no credence to). There is no denial of the outward existence, only the negation of any reality other than the Only True Reality (That which is left when all else is gone). Look how even the basest tyrants act according to this law, seeking to physically destroy their enemies and succeeding only at self-ruin. Nevertheless the principle is the same - arriving at the truth by a process of elimination.
"Illa" means only, but, if not, except.
"'llah" means Allah, Al-lah! (Arabic) The One. The Conscious Oneness. The Unity. The Divine, The Beyond-Comprehension. The Self-Aware, Who Comprehends All. Existing, Knowing, Seeing, Hearing, Speaking, Willing, The Source of Power. Perfection in and of Itself. Greater than which there is none. Who remains when all else is gone.
This Existence must be both intellectually grasped and physically realized. The Divine "Does" Itself. The full embodiment of the Reality of this Truth is the object in "Quest". Knowing it in our minds may be easy but convincing our bodies takes practice, including verbal affirmations and physical negations. This practice transforms this knowing from a concept to a reality.
Part 2. Muhammadun-Rasulullah
Muhammadun-Rasulullah is a profound summary of the knowledge of creation.
"Muhammad" is the most complex and meaningful word, requiring the study of long eulogies for initial comprehension, so let us summarize. He was indeed the full embodiment of Truth and The Reality, and therefore the way for us to attain this also.
Let's start at the beginning.
Divinity being in and of Itself perfect, should not the first of Its creation be perfection?
In the beginning, and there was no beginning, there was Allah Alone - pure, unmitigated, undifferentiated Oneness. The Divine, The Self-Aware, The Source of Power. And He is now as He was. With no change in His Oneness, He created. His Will and its manifestation are one and the same, and He willed to be known - so that Will manifested in the first of His Creation, a perfect Self-Knowing. But Knowing then did not exist alone, without a knower, so the knower, the perfect self-knowledge, was the first of His Creation. But the knower did not exist without entity, a name and a suitable environment, so the Name was Muhammad (Arabic: The most highly praised one), and the environment was Creation in the four realms.
And why should it not be that way? Creating to be known, should He not create Knowing first? Humans have that knowing innate within them, so, as potential 'knowers', are we not the "Crown of Creation"? Should there not be a perfect one, a prototype, a role model, if you will, that we may seek out to follow and emulate in our own individual search for perfection (read perfect annihilation)?
Rasul means messenger. Messenger implies way. Message is the teaching, Messenger is the way. What the messenger can do, the receiver of the message can do. Implying coming from and returning to the Source of the message. In this case, Allah. 'ullah means to confirm that - (messenger) from Allah.
Evidence from Hadith
Qudsi (traditions spoken by Allah Himself).