Tradition

I (Imam Ali) went to the Prophet (s.a.w.a.) when he was in one of his houses. I asked his permission to enter and he granted it.

When I entered, the Prophet (s.a.w.a.) asked me – O Ali! Do you not know that my house is your house? Why do you seek permission to enter?”

I replied – I like to do that.
The Prophet (s.a.w.a.) said: You like what Allah likes and you use His manners. O Ali! Do you not know that you are my brother, and my Creator did not want me to have a brother other than you? O Ali! You are my heir, and you will be oppressed and wronged after my death. O Ali! Those who are devoted to following you are like those who live with me (in my place in Paradise), and those who abandon you, abandon me. O Ali! Those who think that they love me but hate you, lie because Allah created me and you from the same light.
Kanz al-Ummaal p 208 Ghaayah al-Maraam p 7 Mustadrak al-Wasaail v 2 p 71 Behaar al-Anwaar v 27 p 230