Sowing and reaping is a biblical principle.
However, the actual Tithe was instituted under the Law.
I knew a pastor who used to claim that the Tithe was instituted before the Law. That is a half truth.
A tithe was a tribute/tax. When Abraham tithed to Melchizedek, it was because he was a King, and he gave him a portion of the goods taken from Chedorlaomer.
Giving to our church is something that we should do, but it needs to be done willingly and cheerfully.