LA ILAHA IL LAL LAHU MUHAMMADUR RASULULLAH

Virtues of Kalimah
This Holy Kalimah is the first gateway to the Divine Religion and surest way to keep our Faith refreshed. It has numerous virtues and benefits. We must remain very particular about it and go on reciting it as much as possible. It refreshes and revitalizes our Imaan, the Holy Prophet (Sallallahu 'Alaihi Wasallam) said:
"Keep on refreshing your Faith by reciting Kalimah frequently."

Meaning and Implication: .
The Holy Kalimah consists of two parts:
1st Part LA ILAHA IL LAL LAHU None but Allah is worthy of worship
Allah says in Holy Quran:

Allah! There is no god except Him, the Alive, the Eternal. Neither slumber nor sleep overtaketh Him. To Him belongeth whatsoever is in the Heavens and whatsoever is in the Earth. Who is he that intercedeth with Him except by His leave? He Knows that which is in front of them and that which is behind them, while they encompass nothing of His knowledge except what He will. His throne includeth the Heavens and the Earth, and He is never weary of preserving them. He is the Sublime, the Tremendous. ( 2:255)

Your God is One God; there is no god except Him, the Beneficent, the Merciful. (2:163)

The first part means our compete negation of every creation of Allah, individually or all put together, having capabilities to harm or benefit, and implies our affirmation with with full conviction that:
Allah is one and there is none like Him, He has no partner, He neither beget nor is He begotten; He is indivisible in person: He is Eternal and Infinite. He has neither beginning nor end; He is the Almighty, the All Just and the Sustainer of all: He is the Creator and the Cherisher of all worlds; He has created me and all other beings; it is He Who foster me and all His other creatures; He is All-Knowing. All-Hearing; nothing is concealed from Him; He knows all action I do; He hears all words I speak ; He knows all secrets I keep in my heart; He hears even the whispers of my thought; He is the Dispenser of life and death; sickness and heath, poverty and riches, loss and gain lie solely in His control; He is the Merciful, the Compassionate, the Helper; it is He and only He Whom I must worship; to Him and to Him alone all our prayers and supplications must be addressed; Him and only Him we must fear and hope, His and only His Commandments I must follow.

he 2nd part of the Kalimah is
MUHAMMADUR RASULULLAH Muhammad is His Messenger
Allah says in Holy Quran:

And he (the Prophet) does not speak out of his own desire. It is not but a revelation revealed (to him) (53:3)

Muhammad is not the father of any man among you, but he is the messenger of Allah and the Seal of the Prophets; and Allah is Aware of all things. (33:40)

Muhammad is but a messenger, messengers (the like of whom) have passed away before him..... (3:144)

The second part embodies affirmation with conviction that: Muhammad (Sallallahu 'Alaihi Wasallam) is His Apostle and Prophet; he was a servant of Allah and a human being but selected by Allah to be His Messenger like other previous Apostles and Prophets; Allah's Commandments were revealed to him for the guidance of man; he was charged to teach us the Divine Laws; he practiced the religion himself and taught it to us; whatever he did, preached or taught was only from Allah; he never taught us from his own accord; it is through him only we can know Allah's Commandments. I can not deny his Prophethood and Apostle ship; I believe in whatever he taught and preached; be it seen or unseen, be it in our mental approach or beyond that; I do not worship him but I revere him and consider him a model of divinely appreciated conduct for myself and for humanity at large; his prophethood is final and universal; no other Prophet or Apostle will ever now come; to obey him is exactly to obey Allah; to love him is exactly to love Allah the code of life taught us by him is complete and final; we cannot change it; anything running counter to this code is false, anyone going against his ways is cursed.

Reward

After every prayer whoever recites this Kalima 10 times will be bestowed with 20,000 sawaabs(rewards). Above this, whoever recites 100 times, between him and paradise the only hurdle is death. Immediately after he will enter the Paradise.

Obligations
The above explanation of the Holy Kalimah proclaims clearly that this is a pledge: a covenant to follow only Allah's Commandments in every walk of our life and to subject all our internal and external activities solely to His Will. We have to fulfill this pledge and lead our life exactly as the Holy Messenger of Allah Muhammad (Sallallahu 'Alaihi Wasallam) taught us. We must fulfill this obligation with our utmost sincerity and with full devotion. We are bound to seek knowledge of Allah's Commandments and practise them in all spheres of our life. We must worship Him only through the ways that He Himself has prescribed for His worship, must abstain from such deeds and actions that He has forbidden; must deal with His creation only in accordance with His Laws and must perform all our other social or individual affairs even like earning, spending, sleeping and resting etc. . only in such a way as pleases Him