Luke 6:45 A good man brings good things out of the good stored up in his heart, and an evil man brings evil things out of the evil stored up in his heart. For the mouth speaks what the heart is full of.
Once again Jesus teaches us that our own mouths are going to let us down at some stage in our lives.
He further warns us the things which come out of our mouths will most likely echo what is deep in our hearts; when we get angry, we say things because that is how we actually feel deep inside.
It is sometimes only after we say things we realise what is in our own hearts; then we can make amends and change with God’s help!