Reb Mendel told the following a few times:
Once, when he was a child some misnagdishe bochurim were staying in his house (in those days there were less boundaries between misnagdim and chassidim, and it was a normal thing for misnagdim to be hosted by a chosid).
The misnagdim took issue with the fact that the chassidim acted like they had a monopoly on mesirus nefesh, as if no one else has any shaychus to mesirus nefesh. In the course of the conversation, they said to Reb Zelig Aronow: "you think we never practice mesirus nefesh? Sometimes we are walking in the street and we pass a theater, and we refrain from going inside, and that could take mesirus nefesh!"
Reb Yehoshua Zelig said to them "ich gloib nisht az far mein bord vell ich krigen olam habo"!
(Reb Mendel explained that wearing a beard then was literal mesirus nefesh just to walk in the street like that. But, while they wanted to credit themselves for abstaining from going into a theater, he didn't think he deserves any special credit for his beard).
