Sohayl bin Hunayf Ansari was a favourite companion of Imam Ali (a.s). At the time of Imam's return from Siffin, he died at Kufa of the wounds sustained in the battle. His death left Imam Ali (a.s) very sad and he said:
"Even if a mountain loves me it will be crushed into bits. (it means people are tested with my love, and to prove it they have to pass through loss and calamities)."
Ref: Nahjul Balagha, Saying # 111