KALIMAH كلمة
Lit. “The Word.” The Creed of the Muslim.
لا اله الا اله محمد رسول الله
La Ilaha illa ‘llahu: Muslim Rasulu llah.
“There is no deity by God: Muhammad is the Apostle of God.”
The whole sentence as it stands does not occur in the Qur’an; but the first part of the creed, “There is no deity but God,” is in the Auratu Muhammad, or XLVIIth chapter of the Qur’an, verse 21; and the second part, “Muhammad is the Apostle of God,” is in the Suratu ‘l-Fath, or XLVIIIth chapter, verse 29. The first sentence is known as the Nafy and the Isbat, or the rejection (there is no deity) and the affirmation (but God), and is recited often as a religious office by the Suri faqirs.
The whole creed frequently occurs in the Traditions, and is an oft-recurring clause in the daily prayer.
This Kalimah occupies a similar place in the Muslim religion to the “Shema Israil” of the Hebrew Bible in the Jews’ religion. The Shema’ (“Hear”) is the fourth verse of Deut. vi: “Hear, O Israel, Jehovah our Elohimis one Jehovah”; which is frequently used in daily morning and evening service of the Jews. From the Traditions (Mishkat, book xi. ch. pt. 1) it appears that a something similar to this well known symbol of the Muslim creed, was in use amongst the ancient Arabians, and is still recited by Muslims, amongst whom it is known as the Talbiyah: “I stand up for Thy service, O God! There is no partner with Thee.” [TALBIYAH.]
The recital of the kalilmah is the first of the five foundations or pillars of practice, and, according to the Fawa’idu ‘sh-Shari’ah, every Muslim should recite it aloud at least once in his lifetime, and he should understand its meaning. [RECITAL OF THE CREED.]

Based on Hughes, Dictionary of Islam