The third aspect is: The restriction mentioned in the Ayah is made through the dative case which is of the third type of semantics that refer to restriction. So, if the most important meaning had been preserving the Qur'an alone, the Ayah would have mentioned the Qur'an in words through the following:
1- By the real restriction.
2- By using (not only, but also) which refers to the restriction in the first place.
3- Or by using (furthermore) which refers to the restriction at least of the second type. So, using the dative case is not for restriction but for maintaining the rhythm of the Ayahs. Moreover, if there had been a restriction in the Ayah to something in particular, it would not have been the Sunnah. That is because: Preserving the Qur'an depends on preserving the Sunnah.
- Protecting the Sunnah is also protection to the Qur'an because the Sunnah is: its fortified fort, its strong shield, its trustworthy keeper, its obvious explanation which details its general meaning, interprets its confused matters, explains its ambiguous meanings, restricts its absolute, and details its abridged meanings. Moreover, it pushes away the mess of the mischievous, the diversions of the forgetful, and their interpretation of the Qur'an according to their desires and whims and according to their leaders and devils. So, protecting it is one of the reasons of protecting the Qur'an and maintaining the Sunnah is maintenance of the Qur'an.
The fourth aspect is: Allah (may He be Exalted) undertook to protect the Sunnah as He has protected the Glorious Qur'an, therefore, nothing of it has been lost, thanks to Allah, even if not every person can encompass it all.
Imam Ash-Shafi`y (may Allah bestow mercy on his soul) said in his message about Lisan Al `Arab Book: "Lisan Al `Arab is the most comprehensive lexicon and contains more words than any other lexicon. We do not know that anyone can know all of it except a prophet. However, nothing of it is lost though its wide scope of words to the extent that no one can encompass it."(1) knowing it according to the Arabs is like knowing the Sunnah to the people of Fiqh: We have not heard of a man who memorized all Hadiths without losing any of it. If a person gathers the knowledge of scholars, he will become acquainted of all the Sunnah. However, if the knowledge of each one of them is separated, a person will not know everything about it. So, a person always finds the knowledge that he does not have at others. People are divided into several classes in regard of narrating the Hadith: Some of them know more even if they lost some other knowledge and some have less knowledge than others. The Hadiths that were lost and only exist at some narrators who are less in rank is a proof that a person may seek knowledge from other compliers even if they are less in the knowledge of Hadith. Furthermore, a person may ask his counterparts for the knowledge that he missed until all the Sunan of the Messenger of Allah (peace be upon him) is gathered at some scholars; and those scholars are divided into ranks in regard of the Hadiths which they missed." (2)
1- As reported in Ar-Risalah, and it is correct that depending of the negative form, but also) otherwise we should omit There was nothing (behind it).
2- Ar-Risalah p. 42- 43.