Three chassidim are sitting around a table on Motzei Shabbos telling over Rebbeshe ma’asos while eating their Melava Malka. The Rebbe walks by, and asks them what they’re doing. They respond, “It’s a minhag to tell over Rebbeshe ma’asos on Motzei Shabbos!”
The Rebbe replies, “Lav davka”, and walks away.
The first chassid says, “Lav davka on Motzei Shabbos – it should be all week!”
The second one says, “Lav davka Rebbeshe Ma’asos – we should say over all types of ma’asos!”
The third one says, “Lav davka it’s a minhag – it’s a chiyuv!”