An extraordinary incident of brotherhood....
On the day of the battle of Yarmuk, I went out to find my uncle on the battlefield, and I had with me a container of water. I said to myself that he had some life left in him, then I would quench his thirst with the water and wash the dirt from his face. Suddenly, I came across him, and he was going in and out of conciousness. I asked him: "Do you want me to give you some water?" so, he nodded his head. Suddenly, he heard another wounded man in the distance calling out in pain. So, my uncle motioned for me to go tend to him. I went to him and saw that he was Hisham, the brother of 'Amr bin al-'As. I came to him and asked if he wanted me to give him some water, and suddenly, we heard the sound of another man calling out in the distance in pain. So, he motioned for me to go tend to him. I came to him to find that he had already died. So, I went back to tend to Hisham only to find that he had died as well. Then, I went back to tend to my uncle only to find that he, too, had died." So none of them, in their love for others had died without quenching their thirst. Such a proof of sacrifice and brotherhood is unparalleled in human history.
This incident was reported by 'Abdullah bin al-Mubarak in 'az-Zuhd' (1/185), Ibn Hajar in 'al-Isabah' (7/34), and also in Ibn al-Mubarak's 'al-Jihad' (1/100) by way of Abu al-Jahm bin Hudhayfah al-'Adawi, by way of 'Umar bin Sa'id. The muhaqqiq of 'al-Jihad' mentions that the chain's narrators are all trustworthy, and Allah Knows best.