The Prophet Muhammad (SAWA) was asked when he recited this verse on the Muslims: Is it ordering us to do good to our kin or your kin? He replied: My kin; Ali, Fatima, and their sons. (Al-Haakim al-Hasakaani in Shawaahid al-Tanzeel , V. 2, P. 189) and Tafseer al-Qurtubi, V.3, P. 2.) . These are among Sunni references and among Shia references you can refer to Al-Kaafi 1:413.
We take the meanings of Quran from the Prophet (SAWA) as we were been ordered by Allah (SWT).