The Prophet’s (saw) Kin
When the verse 3:61 was revealed to the Prophet (saw): “Now that you know the facts, say to them ‘Come, let us summon our sons and your sons, our women and your women and ourselves and yourselves and pray Allah and beseech Him to accurse those who intentionally assert falsehood’”; he summoned Ali, Fatima, Hassan and Hussain and said: “O God, & these are my kin”.
How can a believer not love Ali
Zirr reported: ‘Ali observed: By Him Who split up the seed and created something living, the Apostle (may peace and blessings be upon him) gave me a promise that No one but a believer would love me, and none but a hypocrite would nurse grudge against me.
Reference: Book 001, Number 0141: (Sahih Muslim)
He whom Allah and His Messenger (saw) love
Narrated Salama: Ali happened to stay behind the Prophet and (did not join him) during the battle of Khaibar for he was having eye trouble. Then he said, “How could I remain behind Allah’s Apostle?” So ‘Ali set out following the Prophet . When it was the eve of the day in the morning of which Allah helped (the Muslims) to conquer it, Allah’s Apostle said, “I will give the flag (to a man), or tomorrow a man whom Allah and His Apostle love will take the flag,” or said, “A man who loves Allah and His Apostle; and Allah will grant victory under his leadership.” Suddenly came ‘Ali whom we did not expect. The people said, “This is ‘Ali.” Allah’s Apostle gave him the flag and Allah granted victory under his leadership.
Reference: Volume 5, Book 57, Number 52: (Sahih Bukhari)
He was to the Prophet (saw) what Haroon (as) was to Musa (as)
Sa’d reported Allah’s Apostle (may peace be upon him) as saying to ‘Ali: Aren’t you satisfied with being unto me what Aaron was unto Moses?
Reference: Book 031, Number 5916: (Sahih Muslim)
For whosoever is Prophet (saw) Mawla, Ali is Mawla
Sayyidna Abu Sarihah (Radhi Allah) or Zayd ibn Arqam (Shu’bah is uncertain about it) said that Prophet (salallaho alaihi wasalam) said: He for whom I am Mawla (friend, beloved, helper), Ali is Mawla
Reference: Sunan al Tirimdhi Hadith No. 3733 – Imam Abu Isa Tirimdhi (rah) said: This Hadith is “HASAN SAHIH”