The Prophet—peace and blessings be upon him—said in the well-known authentic hadith:
“I have been commanded to fight the people until they testify that there is no deity except Allah and that I am the Messenger of Allah. Once they say this, they have protected their lives and property from me, except by its due right, and their reckoning is with Allah.” (1)
The Prophet—peace and blessings be upon him—also said in an authentic hadith:
“Whoever dies knowing that there is no deity except Allah will enter Paradise.” (2)
He also said:
“Whoever’s last words are ‘There is no deity except Allah’ will enter Paradise.” (3)
The entire Quran is replete with establishing this tawhīd and calling people to it, making salvation and success contingent upon it and showing that happiness in the Hereafter is attained through it. It is well known that people differ in the degree to which they realize it. Its true essence is to devote the whole of religion sincerely to Allah.
Fanā (passing away) in this tawhīd is coupled with baqā (abiding) (4). This means affirming in your heart the divinity of the True One while denying divinity to all besides Him, thereby combining negation and affirmation. Thus, you say, “There is no deity except Allah.” Negation is fanā, while affirmation is baqā.
Its true essence is that, through worshipping Him, you turn away from all besides Him; [through loving Him, from loving all besides Him] (5); through fearing Him, from fearing all besides Him; through obeying Him, from obeying all besides Him; through showing loyalty to Him, from showing loyalty to all besides Him; through asking Him, from asking all besides Him; through seeking refuge in Him, from seeking refuge (6) in all besides Him; and through relying upon Him rather than relying upon