Matthew 7:12 (New International Version, ©2011)
12 So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets.
Sometimes we ought to help a friend in need cos if we were in that position, we would want them to help us as well. Likewise, we would not do something to a friend which we wouldn't want them doing to us.
The tongue is mightier than the sword, hence the words we say to others, we must be sure, we won't want to be said to us. I'm actually not hurt by words that people say to me that are degrading or insulting or just plain taking a 'dig' at me, but if they didn't want the exact same words thrown back at them, they should think twice before saying such things. So much for practising what you preach.