'Although initially this outcome was merely contingent and possible, when the eternal Word of Allah connected with it, it became necessary, final, and inabrogable,
for Allah only informs of what is in His knowledge, and His knowledge only conforms to what truly is, which is why no one alters the words Allah (Qur'an 6:34), for otherwise His words would express ignorance,an attribute impossible for God, or lies, which equally contradict the nature of the Divine'
http://www.masud.co.uk/ISLAM/nuh/amat.htm