Following the Prescribed Order of Tithes

"The fullness of your [harvest] and of the outflow of your [presses] you shall not delay"Exodus 22:28.

It is forbidden to deviate from the order of the harvest's tithes prescribed by the Torah.

Bikkurim [the first fruits taken to Jerusalem and given to the priest] is the first gift that is given from the harvest. Afterwards one separates 1/50 of the remaining crop for Terumah. Then one separates 1/10 of the remainder, the First Tithe. Then one separates 1/10 of the remainder, the Second Tithe. The Terumah is given to the priest, the First Tithe to the Levite, and the Second Tithe is eaten by the owners in Jerusalem.

If this order was not followed, i.e. if one separated a later tithe before one that should have preceded it – though the action is valid – he has transgressed this prohibition.