The second sentence of the Shahada indicates the means by which God has offered guidance to human beings. Islam's monotheistic nature is reflected in the first sentence of the Shahada, which declares belief in the oneness of God and that he is the only entity truly worthy of worship. It appears in these forms about 30 times in the Quran, and never attached with the other parts of the Shahada in Sunni or Shia Islam or 'in conjunction with another name'. It appears in the shorter form lā ʾilāha ʾillā huwa (There is no deity but Him) in many places. In the Quran, the first statement of the Shahadah takes the form lā ʾilāha ʾillā llāh twice ( 37:35, 47:19), and ʾallāhu lā ʾilāha ʾillā huwa (God, there is no deity but Him) much more often. In Shia Islam, the Shahada also has a third part, a phrase concerning Ali, the first Shia Imam and the fourth Rashidun Caliph of Sunni Islam: وَعَلِيٌّ وَلِيُّ ٱللَّٰهِ ( wa ʿalīyun walīyu llāh ), which translates to 'Ali is the wali of God'. The first statement of the Shahada is also known as the tahlīl. In Sunni Islam, the Shahada has two parts: 'lā ʾilāha ʾillā -llāh' ('There is no deity except God'), and 'muḥammadun rasūlu llāh' (' Muhammad is the Messenger of God'), which are sometimes referred to as the first Shahada and the second Shahada. The expression al-šahīd ( ٱلْشَّهِيد, 'the Witness') is used in the Quran as one of the ' titles of God'. The Islamic creed is also called, in the dual form, šahādatān ( شَهَادَتَان, literally 'two testimonies'). The noun šahādah ( شَهَادَة), from the verb šahida ( شَهِدَ), from the root š-h-d ( ش-ه-د) meaning 'to observe, witness, testify', translates as 'testimony' in both the everyday and the legal senses.

Muhammad is the Messenger of God.' – the first, lower-case occurrence of 'god' or 'deity' is a translation of the Arabic word ilah, while the capitalized second and third occurrences of 'God' are translations of the Arabic word Allah, meaning 'the God'. In the English translation – 'There is no deity but God. The above two statements are commonly prefaced by the phrase ašhadu ʾan ('I bear witness that'), yielding the full form:

No god but god book