When was the phrase: (There is no god but Allah) revealed in the Quran, and what is the first surah in which the word of Tawhid (monotheism) was mentioned?

The first revelation of the Qur’an was the verse: "Recite in the name of your Lord who created," which is an indication of the Oneness of Allah. Then, the beginning of Surat Al-Muddaththir was revealed, containing an invitation to Tawhid (monotheism) through the command to warn the polytheists, glorify Allah, and abandon idol worship. Furthermore, Surat Al-Muzammil, which is among the earliest revelations, explicitly states the word of Tawhid in the verse: "Lord of the East and the West; there is no deity except Him, so take Him as Disposer of affairs." It is clear that Tawhid and the prohibition of polytheism are the essence of the Prophet’s (peace be upon him) message, and among the first commands revealed in the Meccan Qur’an.