Thirteen years the Prophet ﷺ was proclaiming that [Laa ilaha illAllah] in Makkah, just Laa ilaha illAllah, that's it. The most important thing in Laa ilaha illAllah is that you must act on it.
Laa ilaha illAllah that's the most important thing, the Prophet ﷺ spent thirteen years in Makkah inviting people to Laa ilaha illAllah!
And he sent Mu'adh to Yemen and he told Mu'adh, Mu'adh when you get there and you see the people of the scripture, the Christians and the Jews, the first thing to invite them to (is) Laa ilaha illAllah.
Laa ilaha illAllah - you must act practically on its legal order and obligation. [This is another definition].
This is important, this is the first thing in Islam, the pillar of Islam, the most important thing, this one, laa ilaha illAllah.
The pillars of Islam, this one's first.
- Shaykh Musa Jibril حفظه الله