It is narrated that in the Battle of Siffin an arrow entered the blessed thigh of the first Shia Imam, Ali ibn Abitaleb (AS) and it was not possible to pull it out normally due to extreme and unbearable pain. Imam Hussain (AS) was informed about the situation and he said: Wait until my father starts performing Salaat/Salaah because in that situation he is so focused that will not realize anything else. The arrow was removed as instructed by Imam Hussain (AS). After Salaat Imam Ali (AS) noticed blood on his leg and asked what happened? They said: When you were performing Salaat, the arrow was pulled out [1].
[1] Anwar-i-Noa’maniyeh, Seyyed Jazayeri, Page 342.