Some think this might indicate that Mark did not use a complete Jewish Bible but instead used a general collection of quotations from them. Protestant theologian Heinrich Meyer suggests that the reference to Isaiah is authentic but it was a "mistake of memory". The quote appears to be a composite from the books of Exodus (), Malachi () and Isaiah (), linking the gospel of Jesus with a fulfillment of the "Old Testament". Mark assumes they refer to John the Baptist or applies them to him.