Love of the Prophet’s Family and His Companions is a sign of the Ahle Sunnah
There is a Hadith in Jame’ Tirmidhi:
Translation: It is narrated on the authority of Hadhrat ‘Abdullah bin ‘Abbas (May Allah be well pleased with them) that the Holy Prophet (Sallallahu alaihi wa sallam) said: Love Allah Most High as He grants you bounties. Love me to love Allah and love Family to love me.
(Jame' Tirmidhi, Vol. 2, Pg No. 219; Mishkaat Ul Masabeeh, Vol. 2, Pg No. 573; Zujajatul Masabeeh, Vol. 5, Pg No. 314/315)
The grace and benevolence of Allah Most High demands that we should love Him. To be able to love Allah Most High, we should love the Holy Prophet (Sallallahu alaihi wa sallam) and to be able to love the Holy Prophet (Sallallahu alaihi wa sallam), the Prophet’s Family should be loved.
It is as if the love of the Prophet’s Family is a step towards the love of the Holy Prophet (Sallallahu alaihi wa sallam). If anybody desires proximity and closeness of Allah Most High and wants to be summoned unto His presence, the only way for this is to love the Prophet's Family. This love will grant closeness to the Holy Prophet (Sallallahu alaihi wa sallam) and through the proximity of the Holy Prophet (Sallallahu alaihi wa sallam), one can attain proximity of Allah.
There is a Hadith in Sunan Ibn Majah and Jame’ Tirmidhi.
Translation: The Holy Prophet (Sallallahu alaihi wa sallam) said: By Him who holds my life in His hands, faith cannot even enter the heart of the person, who does not love you (The Prophet’s Family) for the sake of Allah Most High and the Holy Prophet (Sallallahu alaihi wa sallam). (Jame' Tirmidhi, Vol. 2, Pg No. 217, Hadith No: 3691)
In the Hadith of Ibn Majah, the words are:
Translation: Until he loves them for the sake of Allah Most High and because of my relationship with them. (Sunan Ibn Majah, Pg No. 13, Hadith No: 137)