Commentary for Niddah 122:41

There are those who explain this according to what is written in ketubot that in the future the dead will be resurrected in their clothing. This is difficult for me because the dead that Yehezkel brought back to life were obligated in mtzvot. As it says in perek Challah (Sanhedrin 92b) "My father from them" in "these are the tefillin that my father from them gave me". It appears to me that in the coming age means from the time of death [the dead will be exempt from mitzvot]. We learn that the living cannot cause the dead to violate a mitzvah, just as a parent cannot cause a child to eat something forbidden. The reason is because is says "the dead are free". Since the dead are freed from mitzvot from the time of death, in the time to come, may it come speedily in our time, we do not want to lead the person astray in the time to come. 

This was only taught for the eulogy, but for burial it is forbidden. Because shatnez is not forbidden by the Torah, but rather wearing, and rising up [from the grave] is comparable to wearing, but the eulogy is only for an individual's honor, and is comparable to one who sells clothing [with shatnez to non-Jews] in the normal manner. However burial is comparable to wearing and because of this, wearing [shatnez] is forbidden for the one who says mitzvot aren't nullified [in the world to come].