The 154th prohibition is that we are forbidden from giving the agricultural gifts out of order; rather, we must give them in the proper order.
The explanation of this is as follows: wheat, for example, which was threshed and piled up has the status of tevel.1 One must set aside 1/50th for terumah gedolah. Then, one must set aside 1/10th of the remainder for ma'aser rishon. After that, one must set aside 1/10th of the remainder for ma'aser sheni. One gives the terumah gedolah to a Kohen; the ma'aser rishon to a Levite; and eats the ma'aser sheni himself in Jerusalem.
This law prohibits either giving earlier that which should come later or delaying that which should come earlier.
The source of this prohibition is G‑d's statement,2 "Do not delay your offerings of newly ripened produce (m'lei'as'cha) and your agricultural offerings (dimas'cha)," i.e., do not delay that which should come earlier.
The Mishneh in tractate Terumos3 says, "One who gave terumah before bikkurim, or ma'aser rishon before terumah, or ma'aser sheni before ma'aser rishon—although he transgressed a negative commandment, as it says, 'Do not delay your offerings of newly ripened produce and your agricultural offerings,' his act is still valid."4
The Mechilta says, "The word 'm'lei'ascha' refers to bikkurim, which are picked only when ripe (m'lai); 'dimas'cha' refers to terumah; 'do not delay' means that one may not give ma'aser sheni before ma'aser rishon, ma'aser rishon before terumah, or terumah before bikkurim." It also says in that passage, "This verse is the source for the law that although one who gave terumah before bikkurim or ma'aser sheni before ma'aser rishon transgressed a negative commandment, his act is still valid."
In the beginning of tractate Temurah5 it is explained that one who violates this commandment does not receive lashes.6
