Sources: www.ahl-ul-bayt.org, www.iqna.ir/en/
QURAN ABOUT LOVE OF AHLUL BAYT: المــوده في القــربى
Surah 42 (Shoora), Ayah 23 demands the love of Ahlul Bayt.
قُل لا أَسْأَلُكُمْ عَلَيْهِ أَجْرًا إِلا الْمَوَدَّةَ فِي الْقُرْبَى وَمَن يَقْتَرِفْ حَسَنَةً نَّزِدْ لَهُ فِيهَا حُسْنًا إِنَّ اللَّهَ غَفُورٌ شَكُورٌ
Declare [O' Muhammad]: “I ask you of no recompense for my toil except the love for my kin (family).” And the one who earns good, We shall expand it for him. Verily Allah is oft‑forgiving and appreciates good works.
Commentary
You reap as you sow, for those who believe and do good (to please Allah) are blessed in this life and especially in the Hereafter.
To know that Ali, Fatima, Al‑Hasan and Al‑Husain and their children are the closest kin “near relatives” of the Prophet (pbuh) is well known.[10]
This verse commands the Muslims to love Ahlul Bayt if they want to repay the Prophet (pbuh) for his toils of Prophethood, thus the Ayah commands (and indirectly demands from) us to follow Ahlul Bayt in word and deed:
▪ because Ahlul Bayt have been wholly purified by Allah Almighty,
▪ because Ahlul Bayt are the truthful ones (Al‑Saadiqeen),
▪ because Ahlul Bayt are the custodians of the Word of the Almighty, and
▪ because Ahlul Bayt are the ones who know the inmost interpretation of the Quran (the Guidance sent for all mankind).
History shows that from the beginning to the end of their lives, every member of the Ahlul Bayt had presented an ideal Islamic pattern of life, not equaled by any among the followers of the Prophet (pbuh), therefore love and devotion to them was commanded by the Quran to provide the highest form of guidance to mankind. Love implies sincere attachment which must manifest in every thought and deed.
Imam Al‑Saadiq once stated, “He who obeys Allah's Commands is our devotee; and he who disobeys Allah's Commands is our enemy.”
[Qurba قربى means nearness. Fil qurba في الـقــــربى means for the sake of nearness].
The structure of the verse proves that the Prophet (pbuh) has been commanded to demand recompense, as an exception, not from every one, but from those believers mentioned in Surah Furqan, Ayah 57‑‑those who take the way to their Lord. The recompense is in the interest of the believers themselves, not in any way profitable to the Prophet (pbuh) in his personal life.
Qurba (nearness) has been used to show that not only relationship but also nearness in character and accomplishment is taken into consideration as the important quality. So, on the basis of this verse, love of the Ahlul Bayt has become an obligatory function of the faith, a fundamental condition for the devotion to Allah and good deeds.]
ref: islamicbooks.info