Tafsir (تفسير, tafsīr, "interpretation") is the Arabic word for exegesis or commentary, usually of the Qur'an. An author of tafsīr is a mufassir. One of the most respected and widely used tafsir is that of ibn Kathir, which uses hadith to explain the meanings of Qur'an verses (as the Qur'an is largely without context).
Many Muslims who deny the more unsavoury aspects of Islam will often attempt to deflect criticism away from the Qur'an by claiming it can only be correctly understood when read in conjunction with an authoritative tafsir. However, more often than not, the tafsirs confirm the views of the critics.