pure monotheism, which is the foundation and foremost principle of religion. Allah accepts no deed without it; He forgives those who uphold it, but does not forgive those who abandon it. As Allah Most High says:

“Indeed, Allah does not forgive associating partners with Him, but He forgives anything less than that for whom He wills. Whoever associates partners with Allah has indeed committed a tremendous sin.”

For this reason, the declaration of monotheism is the finest and greatest of all speech. Thus, the greatest verse in the Quran is Āyat al-Kursī:

“Allah—there is no deity worthy of worship except Him, the Ever-Living, the Sustainer of all existence. Neither drowsiness overtakes Him nor sleep.”

The Prophet, may Allah bless him and grant him peace, said:

“Whoever’s last words are ‘There is no deity worthy of worship except Allah’ will enter Paradise.”

A deity is one to whom the heart turns in worship, seeking help, placing its hope in him, fearing him, revering him, and honoring him.