The last sermon of Prophet Muhammad, sallallaahu ‘alayhi wa sallam
28-4-2005 | IslamWeb
Question:
Did Prophet Muhammad (PBUH) mention anything about his family in his last sermon?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The Prophet, sallallaahu ‘alayhi wa sallam, greatly admonished and advised his nation in his farewell message on the Day of ‘Arafah. He also advised the Muslims to support and respect his family members. Jaabir ibn 'Abdullaah 
said, "I saw the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, in his farewell message on the Day of 'Arafah and he was on his camel called Al-Qaswaa'. I heard him saying: "O People! I have left among you the Book of Allaah, if you hold fast to it, you would never go astray, and I left amongst you my close relatives, support them, respect them, love them and hold them high in esteem…"
The scholars 
mentioned that the wisdom of mentioning his close relatives after mentioning the Quran is that his family would never collectively agree on falsehood; this is what Shaykhul-Islam Ibn Taymiyyah 
mentioned in his book Minhaaj As-Sunnah. Moreover, the Prophet, sallallaahu ‘alayhi wa sallam, advised us about his family in speeches other than the farewell speech. Indeed the creed of Ahlus-Sunnah Wal-Jamaa'ah is that we should love the family of the Prophet, sallallaahu ‘alayhi wa sallam, and we should ask Allaah The Almighty to be pleased with them and forgive them. Additionally, we should take them as allies, and declare ourselves free from those who insult the family of the Prophet, sallallaahu ‘alayhi wa sallam, or humiliate them.
Furthermore, Ahlus-Sunnah Wal-Jamaa'ah love the family of the Prophet, sallallaahu ‘alayhi wa sallam, more than they love their own family, children and relatives. Indeed, Abu Bakr As-Siddeeq told 'Ali, "Being a close relative of the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, is more beloved to me than keeping ties with my own kinship." [Al-Bukhari] 'Umar told Al-'Abbaas “I swear by Allaah, your becoming a Muslim the day you embraced Islam is more beloved to me than Al-Khattaab (my father) becoming a Muslim if he does so.” [At-Tabaraani] This is because of the respect and love the people had for the family of the Prophet, sallallaahu ‘alayhi wa sallam.
To find out who are the family of the Prophet, sallallaahu ‘alayhi wa sallam, please refer to Fatwa: 83446.
Allaah Knows best.