Holding mourning ceremony and expressing our hatred towards killers of son of The Prophet (s) are considered as the most obvious example for expressing our love to house hold of the Prophet (s).
Question:
What is the meaning of Mourning for Imam Husain (A)?
Answer:
Imam Husain (A) as the fifth member of Āl al-‘Abā (People of the Cloak) and one of the Prophet's household (PBUH) was always receiving special attention from the Prophet (PBUH). According to the following verse of the Holy Qur'an: "قُل لَّا أَسْأَلُكُمْ عَلَيْهِ أَجْرًا إِلَّا الْمَوَدَّةَ فِي الْقُرْبَىٰ " I do not ask you for this message any payment [but] only good will through kinship". [1]
Whoever wants to respect the Prophet (P), should venerate his household, and reverence for the Ashura uprising of Imam Husain (A) is, of course, a kind of respect. Also mourning the martyrdom of Imam Husain (A) and crying for the captivity of his family are the clearest examples of the love of the Prophet Muhammad (PBUH) which finally lead to the God's satisfaction and pleasure.
Note:
[1] Surah ASH-SHURAA, verse 23.