Expressed love for the close of kin-Mawaddat al-Qurba (al-Mawaddah Fil-Qurba)

In this Last Word of Allah (Noble Qur'an), Prophet Muhammad (pbuh) is being commanded to ask the believers to love his kith and kin (that is his Ahlul Bayt (Ahl al-Bayt)) and that would be the return of his apostleship. Hence, to Ahlul Bayt (Ahl al-Bayt) has been obligatory (wajib) command of Allah on every Muslim.

Say (O Muhammad, unto mankind): I do not ask of you any reward for it but love for my near relatives. Noble Qur'an (42:23)

Hazrat Abdullah Ibn Masood (RA) narrated: One day, we were accompanying the Prophet Muhammad (pbuh) in one of his journeys when a Bedouin with an orotund voice shouted at us, "Muhammad!"

"What do you want?" answered the Prophet Muhammad (pbuh).

"What is it if an individual loves a people but he does not imitate them in deeds?" asked the Bedouin.

"One will be attached to the one he loves," replied the Prophet Muhammad (pbuh).

"Muhammad," shouted the Bedouin, "Call me to Islam."

The Prophet Muhammad (pbuh) said: "You should declare that there is no god but Allah (SWT) and that I am the Messenger of Allah (SWT), offer the prayer, defray the zakat, fast during the month of Ramadan, and perform the hajj to the Holy House."

"Muhammad," asked the Bedouin, "Do you ask for wage for so?" "No," replied the Prophet Muhammad (pbuh), "I do not take any wage except that you must regard the relatives." "Whose relatives? Mine or yours?" asked the Bedouin. "It is my relatives," answered the Prophet Muhammad (pbuh). The Bedouin said: "Give me your hand so that I will declare allegiance to you. No good is expected from him who loves you, but not your relatives."(Bihar ul-Anwar) 

Hadith Al-Safinah or Safinah Tradition

Prophet Muhammad (pbuh) has compared his Ahlul Bayt (Ahl al-Bayt) to Noah's ark. Whoever loves and follows them will attain salvation and whoever violates their sanctity will drown. While holding the door of Holy Kaaba, Abu Dharr told that he had heard Prophet Muhammad (pbuh) say, "My family among you is like Noah's ark. He who sails in it will be safe, but he who holds back from it will perish."

In another place Prophet Muhammad (pbuh) said: "The parable of my Ahlul Bayt (Ahl al-Bayt) is that of the boat of Noah, whoever gets aboard it is saved and whoever stays away from it is drowned." 

Hadith al-Thaqalayn or Saqlain Tradition (Hadith of the two weighty things)

Prophet Muhammad - may Allah bestow peace and benedictions upon him and his pure Progeny - said: "Verily, I am leaving behind two precious things (thaqalayn) among you: the Book of Allah and my kindred (itrah), my household Ahlul Bayt (Ahl al-Bayt), for indeed, the two will never separate until they come back to me by the Pond (of al­Kawthar on the Day of Judgement)." [Hadith-e-Saqlain]

Since the Ahlul Bayt (Ahl al-Bayt) carry as much weight in the eyes of Allah as the Noble Qur'an, the former has the same qualities as the latter. Just as the Noble Qur'an is true from beginning to end without the shadow of untruth in it, and just as it is incumbent (duty) of every Muslim to obey its commands, so also must the Ahlul Bayt (Ahl al-Bayt) be perfectly true and sincere guides whose commands must be followed by all. Therefore there can be no escape of accepting their leadership and following their creed and faith. The Muslims are bound by the Hadith of Prophet Muhammad (pbuh) to follow them and no one else.

Conclusion: Prophet Muhammad (pbuh) and his Ahlul Bayt (Ahl al-Bayt) sacrificed all the worldly comforts and even their lives in order to convey the true religion of Islam to us. In return of their sacrifices, we are commanded by Allah to love them. The aim is that through their love, we follow their footsteps. We follow the true teachings of Islam taught by them, so that we live a good and decent life in this world and earn the pleasure of Allah in the life hereafter.