Our 3rd Imam, Imam Hussein (as) was very kind and always thought about others before himself.
When Imam Hussein (as) was traveling to Karbala knowing what was going to happen to him and his family, he met Hazrat Hurr – the commander of Yazid army and his soldiers. Imam Hussein (as) knew that this was the army sent by Yazid ibn Muawiya to fight Imam Hussain (as) and his followers.
This was the army that was going to stop Imam Hussain (as) and his followers from getting water. This was the army who was going to kill Imam Hussein (as) and his family and friends.
Although Imam Hussain (as) knew all this, when Imam Hussein (as) saw how thirst the army looked and that they had no water, Imam Hussein (as) immediately told his men to give their water to the army of Hazrat Hurr.
Not only did Imam Hussein (as) and his men give water to the army but also to their horses.
Moral of the Story: No matter how horrible someone is to you, you should always be nice to them because that is what Allah (SWT) has taught us.