A BOOK OF TAFSIR IS NOT THE SAME AS THE QUR'AN
Question:
Why is the following verse not written on Tafsir books : None can touch but purified : [1]
Answer:
Since a Tafsir book contains words of men, it is like all other religious books: a person who is impure may touch it, even if all or more of the Qur'an is written in it. What is forbidden is for an impure person to touch a copy of the Qur'an, which either consist of the Qur'an by itself or what is for the most part of the Qur'an.
1.Al-Waqi'ah 79
Permanent Committee for Research and Verdicts
Fatawa Islamiyah Darussalam Vol : 7 page no. 130