A guy was scared that when people would think that he died, he would really still live, and be buried alive, so after he died, his son found a "tsavo'o" with his wish to be buried only 2 weeks after his death, so to be sure that he really passed away.
So they had a problem, from one side, there is "mitsva lekayem divrei hames", and on the other hand, there is "kovod hames", so he needs to be buried straight away.
They went to ask the rabbi, who thought for a few seconds, and exclaimed:"he needs to be buried right away!"
At the shiva, when the rabbi came to be menachem, the son asked the rabbi: I'm not doubting your psak, I was just wondering, how the rabbi concluded the halocho.
So the rabbi replied: If your father really died, then whole point why he wants to wait, falls away, so you can bury him now, and he really is still alive, there is no mitsva lekayem divrei hames.