'Sign' in the Bible

Now please swear to me by the Lord that you will also show kindness to my family, because I showed kindness to you. Give me a sure sign

That this may be a sign among you, that when your children ask their fathers in time to come, saying, What mean ye by these stones?

Then you will say to them, Because the waters of Jordan were cut off before the ark of the Lord's agreement; when it went over Jordan the waters of Jordan were cut off: and these stones will be a sign for the children of Israel, keeping it in their memory for ever.