In the previous two mitzvos, we said that one must affirm that he did not eat his maaser sheini in a state of ritual impurity or in grieving for a just-deceased relative. From these statements, we infer that doing these things is impermissible. There's one more statement we must make from we which derive a prohibition regarding maaser sheini: we must affirm that we did not spend any second-tithe funds "on the dead." Let's examine what this means.
Money of the second tithe could only be used to puchase organic produce that nourishes the body. This includes such items as fruit and meat but not even water or salt. If a person used the money of the second tithe to purchase something he shouldn't, such as utensils, that is a "dead" object in that it does not sustain a person. One may not even purchase objects of a mitzvah, such as a coffin and burial shrouds, which are literally "for the dead."
The reason for this is that God doesn't want us to use the money of second tithe to furnish our homes or whatever. It is to be brought to Jerusalem and eaten there. As we said in Mitzvah #360, the obligation to bring a tithe of animals, people would often use these tithes to support their sons who studied in Jerusalem yeshivos. These tithes were actually instrumental in increasing the number of scholars in the nation.
If someone did violate this mitzvah, he was obligated to take a sum equal to the amount he misappropriated and use it for its intended purpose.
This mitzvah applies in Temple times. It is discussed in the Mishna in the fifth chapter of tractate Maaser Sheini. It is codified in the Mishneh Torah in the third chapter of Hilchos Maaser Sheini. This mitzvah is #152 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos.