Say to them ‘Who can guard you preserve you by night and day from the Compassionate One?’ from His chastisement if it should befall you? In other words no one can do such a thing. Those being addressed here do not fear God’s chastisement because they deny the truth of it. Nay but of the Remembrance of their Lord that is the Qur’ān they are disregardful failing to reflect on it.