Hazrat Ali (radhiyallahu ‘anhu) reports that on one occasion, Rasulullah (sallallahu ‘alaihi wasallam) attended the janaazah of a certain Sahaabi. He thereafter addressed the Sahaabah (radhiyallahu ‘anhum) who were present and said, “Who among you will go back to Madinah Munawwarah, and wherever he sees any idol or statue, he will break it, and wherever he sees any grave which is raised (high above the ground, or has a structure built on it), he will level it (to the correct height), and wherever he sees any picture (of animate objects), then he will immediately destroy it?”
Hearing this, a certain Sahaabi volunteered saying, “I will do so, O Rasul of Allah (sallallahu ‘alaihi wasallam)!” However, before entering the city, he was overcome by fear of his people, and hence he returned to Rasulullah (sallallahu ‘alaihi wasallam) and expressed his inability to fulfil such a task. Hazrat Ali (radhiyallahu ‘anhu) was present, and he said to Rasulullah (sallallahu ‘alaihi wasallam), “I will go, O Rasul of Allah (sallallahu ‘alaihi wasallam)!”
Hazrat Ali (radhiyallahu ‘anhu) then went to Madinah Munawwarah and completed the mission he was tasked with. On returning, he said to Rasulullah (sallallahu ‘alaihi wasallam), “O Rasul of Allah (sallallahu ‘alaihi wasallam)! I did not leave, in the city, any idol or statue, except that I broke it, nor any grave (that was raised above the correct height), except that I levelled it (to the correct height), nor any picture (of animate objects), except that I destroyed it.”
Rasulullah (sallallahu ‘alaihi wasallam) thereafter said, “The one who returns to doing any of these things (i.e. raising the graves high above the correct height or building structures over them, or making pictures of animate objects), then he has shown complete disregard and ingratitude to that which has been revealed to Muhammed (sallallahu ‘alaihi wasallam) (i.e. he has shown ingratitude to the laws of deen which were revealed to Rasulullah (sallallahu ‘alaihi wasallam)).” (Musnad Ahmed #657)
From this incident, we see the outstanding bravery and unique courage of Hazrat Ali (radhiyallahu ‘anhu), together with his eagerness to always fulfil the blessed command of Rasulullah (sallallahu ‘alaihi wasallam).