Tom He was speaking to OT people. The law was still in effect for the tithe. That passage does not apply to the church since the church was not born yet.
This is a good example of "where you start determines where you come out."
I'm assuming that since you hold that the church was not yet born, you hold that it was formed on the Day of Pentecost. That view would place Jesus' endorsement of the tithe in an OT law setting.
My view is that Jesus himself personally established his church during his earthly ministry. I hold that it was essentially in existence when he completed calling the Twelve, and that they formed the nucleus.
Jesus not only established his church, he built it.
He empowered it ("even the demons are subject to us.").
He established the ordinances (Jesus baptized not, but his disciples did).
(The Lord's Supper is "the New Testament in my blood").
They had a commission early on (he sent out the seventy).
They had a commission later on ("Go ye therefore...")
They had a message ("Repent, for the kingdom of heaven is at hand")
They had a Head, Jesus himself.
They had a treasurer (Judas).
They had a business meeting (to choose Judas' successor).
All of this prior to Pentecost.
So, if my view is correct, then Jesus' teaching about tithing occurred during a New Testament setting, since his church existed prior to Pentecost.