This entry is the baseline, written from the sources cited. No reviewer has checked it yet.
The Concept of One God
The Quran states that there is no god except one God, and that Allah is the only deity.1,2Allah is described as the Ever-Living, the Sustainer of all existence, to whom belongs whatever is in the heavens and on the earth.3,4People were commanded to worship one God, and those who say Allah is the third of three have disbelieved.5,1
Affirmation of Tawhid
The Messenger of Allah ﷺ said that Islam is raised on five pillars, including testifying that there is no god but Allah.6The Prophet ﷺ commanded to exhort those who are dying to recite, "There is no god but Allah."7,8One who professes that there is no god but Allah and denies everything worshipped beside Allah has their property and blood inviolable.9
Consequences of Denying Tawhid
Those who say, "Allah is the third of three," will be afflicted with a painful punishment if they do not desist.1When it was said to some, "There is no deity but Allah," they were arrogant.10Those who invent a lie about Allah are most unjust and will be presented before their Lord.11
Remembrance of Tawhid
The Messenger of Allah ﷺ said that whoever says in the morning, "There is no god but Allah alone Who has no partner; to Him belong the dominions, to Him praise is due, and He is Omnipotent," will have a great reward.12The Messenger of Allah ﷺ used to supplicate during times of trouble with the words: "There is no god but Allah, the Great, the Tolerant."13The Messenger of Allah ﷺ recited "Say: He is Allah the One" in the two Rak'ah after Al-Maghrib and before Salatul-Fajr, and during the two Rak'ah of Tawaf.14,15