Quranic Methods for Calling to tawḥīd al-ulūhiyyah (the exclusive worship of Allah):
Because tawḥīd al-rubūbiyyah (acknowledging Allah’s lordship) is already admitted by people through their innate nature and their contemplation of the universe—and because merely acknowledging it is neither sufficient for true faith in Allah nor a safeguard against punishment—the messengers focused their summons on tawḥīd al-ulūhiyyah. This was especially true of the mission of the Seal of the Messengers, our Prophet Muhammad—upon him and upon them be the most excellent blessings and peace. He would require the people to declare lā ilāha illā Allah (there is no god but Allah), a declaration that entails worshipping Allah and abandoning the worship of anything else. They recoiled from him and said, “Has he made all the gods into one God? Indeed, this is something astounding!” 1 They tried to persuade the Messenger to give up this call and to leave them to their idols, using every means at their disposal—sometimes by tempting him, at other times by threatening him—while he, may blessings and peace be upon him,