It is narrated from the Prophet of Islam (PBUH) who said:

I am your (God appointed) Mowla (Guardian, Trustee and Helper), do not cut your connections with me. The reward for my efforts (for you all) is that you remain friends to (Imam) Ali (AS) and his children (the eleven infallible Imams (AS) after him). Remain friends of Itrah Tahirah (Ahlul Bayt (AS)). When their names are mentioned your hearts open up and you feel joyous. Accept their commands and obey them. The reward for my prophethood is to be kind to them (Ahlul Bayt (AS)). Kindness is the result of recognition/knowledge (Ma’a’rifah) and recognition is the result of obedience (Ita’at) [1].

[1] Shamim-e-Welayat, the Grand Ayatollah Javadi Amoli, Page 230.

Source: en.shafaqna.com