Your need is greater than mine
There was once a soldier, a Major, who was on the battlefield. He asked his fellow soldier to get him some water as he was thirsty and his throat was parched. The constant days of battle were taking a toll on him. The young soldier ran to fetch him a bottle of water from the nearest campsite.
When he came back and offered the Major a drink, the Major saw a dying soldier about 25 meters away wistfully looking at the drink. The Major told the soldier - "Go give the drink to that soldier there", pointing his finger across the field. The young soldier ran towards him.
The dying soldier asked him - "Why are you doing this?"
the Major replied, "Your need is greater than mine".