By giving the firstfruits we acknowledge God as the Owner of our money and this puts it under His blessing. Only the Lord can define the First Fruits and He says it is the TITHE. Tithing is before the Law (Gen 14:20, 28:22), in the Law (Lev 27:30), and in the New Testament (Matt 23:23, Lk 11:42, Hebr 7:1-8).