In fact...
In fact, this verse is a reference to 'the principle of favor' which is discussed in 'speculative theology' and states that Allah sends clear evidences for every sect to complete the argument. In any case, the meaning of /bayyinah/, here is 'Clear Evidence' and whose example, according to the second verse, is the Messenger of Allah (S), himself, who had at his disposal the Holy Qur'an for his teachings.
The term /suhuf/ is a plural form of /sahifah/ which means 'a leaf or page of a book', or 'some leaves of paper on which something is written' and here it means 'the contents of them', because we know that the holy Prophet (S) could not read anything from the pages and therefore, was teaching the 'contents' of them. And the purpose of using the term /mutahharah/ is that it was exactly the very truth, the original Word of Allah, in its purity, without…