Mu`adh bin Jabal (May Allah be pleased with him) reported: The Messenger of Allah (PBUH) said, "He whose last words are: `La ilaha illallah (There is no true god except Allah) will enter Jannah."[Abu Dawud].
This Hadith says that if a man's tongue spontaneously starts uttering the basic testification of Islam: "None has the right to be worshipped but Allah" just before his death, he will undoubtedly enter Jannah. However, it is not definite whether he will go to Jannah in the first phase or will be admitted to it in the second phase after undergoing a purification process. This depends on the Will of Allah. Yet, admission to Jannah is subjected to his thorough understanding of monotheism and its conditions, that is to say, a complete abstinence from a polytheistic conduct of life. Otherwise, Jannah is likely to be denied to many of the so-called Muslims overtly indulging in polytheism.