Tawheed
The Oneness of Allah
Allah is One — utterly unique, without partner, without body, without likeness. He is the First without beginning and the Last without end. Belief in Tawheed means recognising that all power, sustenance, life and death belong to Him alone, and worship is due to none besides Him.
Qur'an
قُلْ هُوَ اللَّهُ أَحَدٌ · اللَّهُ الصَّمَدُ — Say: He is Allah, the One; Allah, the Eternal Refuge. (Surah al-Ikhlas 112:1–2)
Hadith
Imam Ali a.s: “The foremost in religion is the recognition of Him; the perfection of His recognition is to affirm Him; the perfection of affirming Him is to declare His Unity.” (Nahj al-Balagha, Sermon 1)