IT IS WRITTEN

You can quite clearly see from the following passages that it is not hard to verify what ‘is written’…because it is written in the Torah!

...(as it is written in the Law of the Lord, "Every male who first opens the womb shall be called holy to the Lord") Luke 2:23  

As it is written in the book of the words of Isaiah the prophet, "The voice of one crying in the wilderness: 'Prepare the way of the Lord, make his paths straight. Luke 3:4 

And Jesus answered him, "It is written, 'Man shall not live by bread alone.'" Luke 4:4  

...saying to them, "It is written, 'My house shall be a house of prayer,' but you have made it a den of robbers." Luke 19:46 

...and said to them, "Thus it is written, that the Christ should suffer and on the third day rise from the dead... Luke 24:46  

Our fathers ate the manna in the wilderness; as it is written, 'He gave them bread from heaven to eat.'" John 6:31 

It is written in the Prophets, 'And they will all be taught by God.' Everyone who has heard and learned from the Father comes to me... John 6:45  

And Jesus found a young donkey and sat on it, just as it is written...John 12:14  

"For it is written in the Book of Psalms, "'May his camp become desolate,and let there be no one to dwell in it';and "'Let another take his office.' Acts 1:20

But God turned away and gave them over to worship the host of heaven, as it is written in the book of the prophets: "'Did you bring to me slain beasts and sacrifices, during the forty years in the wilderness, O house of Israel? Acts 7:42

this he has fulfilled to us their children by raising Jesus, as also it is written in the second Psalm, "'You are my Son,today I have begotten you.' Acts 13:33 

And Paul said, "I did not know, brothers, that he was the high priest, for it is written, 'You shall not speak evil of a ruler of your people.'" Acts 23:5 

Next...'YOU HAVE HEARD IT SAID' and the differences between that phrase's use and 'IT IS WRITTEN'...