Is that in the Bible?

This question, though often coming from the best of intentions and concerns, is fraught with error and mistaken.  To ask this question, usually in response to a specific belief or practice, is based upon presuppositions about the Bible. So the place to begin is with an examination of what we believe about the Bible, specifically in regards to its purpose.
Instead of dividing the Bible into Old Testament and New Testament, we need to think in terms of, and divide by, Old Covenant and New Covenant.  We do this simply because Jesus' life, death and resurrection changes everything, literally everything.  The period of the Old Covenant is from the fall of Adam to the crucifixion.  The time of the New Covenant is from the resurrection of Jesus Christ to forever afterwards. 
With that in mind, we can begin to understand the purpose of Scripture.  All the history of the Old Covenant had been given to point us to the coming Christ.  We see how God has formed, directed and helped his people, Israel.  All of the external actions and events point forward to the coming messiah.  In the Gospels, we see the fruition of all that history come out in the life of Jesus.  He completes, fulfills and finishes all of it.  The epistles then, are direction and example of what that work looks like as it spreads out into the world.
This is one reason that the Orthodox Church holds the Gospels as so important.  Jesus' work is the ultimate act of love of God towards all men.
With that in mind, the Old Covenant time is not a place to look to for life example.  Neither are the gospels.  The one exception is this.  If we understand and embrace the Gospels as part of the Old Covenant, we can then rightly use and apply them in the right context.  One could almost say that the gospels take place in an overlap period between the covenants.
So to return to the original question, something being in or not in the Bible is a valid question only insofar as the specific topic being addressed is in the right context.  Is the topic about Jesus' work of saving mankind?  Then the question is valid.  Is the topic in regards to a certain worship practice, for example?  Then one would not expect to see it in Scripture.  There is much that Jesus, the apostles and Paul taught that was not written down.  The Bible is about Jesus and his work of saving mankind.  All other questions are answered in the Life of the church, that is, in the directing power of the Holy Spirit throughout all history.
So, is it in the Bible?  Maybe or maybe not.  But a better way to ask the question is, "Is this what the church has always practiced and believed?"  If no, then reject it.  If yes, then embrace it as a Holy Spirit inspired and directed part of life.  Live it first and then understand it later.