In Quran’s stories there are 3 words about prophet Mohammad’s family, "Ahl"  "Aal", "Ahlulbayt" whose their meanings are so close to eachother. in some hadiths, there’s the term "Etrat" but it is out of Quran’s studies.
In this study by scrutinizing the literal and Quranic meaning of "Ahl", "Aal"  "Ahlulbayt" and by paying attention to Noah (PBUH), Lot (PBUH) and Ibrahim’s lifestyle, in mecca’s verses and emphasizing on Surat al-Tahrim, it will be made clear that in spite of common reasoning being prophet’s wife or child does not guarantee that they won’t be punished in the hell. And even it doesn’t guarantee that they had the spiritual honor and competence of being totally connected to Prophet Mohammad’s family.
Relating to Islam’s prophet as a relative by marriage and a blood relation, is an essential condition but it is not sufficient! Because being Ahlul Bait, is much more comprehensive than being his wife or child.     It plays an important role in understanding completely and truly the verse "Tathir", and its allocation to Ahlulbayt of prophet Mohammad (PBUH).