A group of shias intended playing a prank on a buzurg. One of them pretended to be dead and was placed on a bier. The buzurg was then requested to perform the janaazah salaah.
It was planned that after the second or third takbeer this person will spring out and jump onto the buzurg.
The buzurg asked them to give ghusl to the dead person. They replied, “We have already given him a ghusl.” He told them, “That ghusl is not valid. Repeat the ghusl.”
Hence, they moved the bier away and took it back to their place. Upon opening the bier they found that he had indeed died.
It was for this reason that the buzurg had ordered them to repeat the ghusl because the ghusl that is done whilst alive is not valid. The ghusl has to be given after death.

NOTE: These people had intended playing a prank on the buzurg and Allah Ta`ala had taken revenge on behalf of the buzurg. One should always fear harassing and harming the pious because even their actions that seem to be mistakes are actually correct. It appears in a hadeeth-e-qudsi: “I declare war against those who harm My friends.” (Bukhaari) (Malfoozaat of Mufti Mahmood Hasan Gangohi , vol. 1, p. 423)