Love for Ahl-ul-Bayt is not only a sign of Allah’s love for man but it is also a sign of other truths as follow:
First: Based on several narrations, love for Ahl-ul-Bayt is a proof of one’s noble birth. The Holy Prophet is quoted by Imam Ali as saying to Aba-Dharr:
Whoever loves us, Ahl al-Bayt, must thank Allah for the first blessing… Nobility of birth; for whoever loves us is of noble (i.e. legitimate) birth.
Imam Baqir (AS) has said:
Whoever wakes up in the morning and feels the cool breeze of our love must thank Allah for the first blessing; purity and nobility of birth.
Second: Love for Ahl-ul-Bayt is a proof of purity of heart. Imam Sadiq (AS) has said:
By Allah, none loves us unless those whose hearts have been purified by Allah.
Third: Love for Ahl-ul-Bayt is a sign of true belief and acceptance by Allah. Allah’s Messenger has said:
My Lord made a promise to me that He will not accept any of His servants’ belief without love for Ahl-ul-Bayt.
Amir al-Mu’menin has said:
The Ummi Prophet expressly said to me that no one but a believer loves me and no one but a hypocrite harbors rancor against me.
He has also said:
Even if I strike the nose of a believer with my sword to oblige him to hate me, he will never hate me; and even if I pile all the wealth of the world before a hypocrite to love me, he will never love me. This is because it is a verdict pronounced by the tongue of the Prophet—may Allah bless him and his descendants—as he said: O Ali, a believer will never hate you and a hypocrite will never love you.
Source: erfan.ir