"Q" is claimed to be the earlier document by which Matthew and Luke are derived (with Mark being the other source). The problem with Q is we have no historical bases to say it existed, not a shred. It's not referenced by anyone (else?) or it's existence even hinted at in any writing of antiquity for a simple reason, It just didn't exist. The concept should have been left in the 19th century where it first started along with other half-crocked religious theories that were popping up everywhere at that time.
A Hebrew Matthew.