Allah (SWT) has ordered us to take the meanings of Quran from the Prophet (SAWA) as he is responsible to explain to the people what was been revealed to guide them ( 16:44).
The Prophet himself has clearly stated that the purified persons meant in Quran 33:33 are Ahlul Bayt who are Ali, Fatimah, Hasan and Husain (AS). (Saheeh Muslim, Hadeeth 4450, Tirmithi; Hadeeth 3129 and 3719).
'The Prophet (SAWA) did not allow any of his wives to join the purified who are Ahlul Bayt only. (Tirmithi: Hadeeth 3806)