משנה על במדבר 18:8

From where do we derive that first-fruits must precede terumah, seeing that this one is called “terumah” and “the first” and the other is [also] called “terumah” and “the first”? Rather first-fruits take precedence since they are the first fruits of all produce. And terumah comes before the first tithe also because it is called “first.” And first tithe [precedes second tithe,] because it includes that which is called “first.”