It is narrated that one of the companions of the Prophet (pbuh) once asked the Prophet: 'Prophet of God, give me a comprehensive directive of Islam, after which I need not ask any one else about it'. The Prophet replied: 'Say: I believe in the One God and then remain steadfast on it1'. He said:

'Prophet of God, what is it that poses the greatest potential danger for me?' In response, the Prophet (pbuh) touched his tongue and said: 'This'.

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General Notes:
1. All religious as well as moral goodness is based on and is an extension of the belief in the One God, Who possesses all those attributes, which are explained in the Qur'an. Thus, true belief in the One God will naturally affect all aspects of a person's life positively.