Rabbi Kramer had scheduled a yechidus (private audience) with the Previous Lubavitcher Rebbe on the eve of the seventh day of Pesach 5709 (1949). The Rebbe told Rabbi Kramer to come back Motzei Pesach. On Motzei Pesach Rabbi Kramer noticed the Rebbe looked very tired, so he waited in 770 but didn’t go into yechidus. Rabbi MM Schneerson (before he accepted the leadership of the Chabad movement) saw Rabbi Kramer and asked him why wasn’t going into Yechidus. Rabbi Kramer replied that he saw that the Rebbe is very tired so he doesn’t want to bother him. Rabbi Schneerson answered him “oif a Rebbe darf men nit rachmonus hobin” (“for a Rebbe one needn’t have mercy”) so Rabbi Kramer went into yechidus.
A few years later, after Rabbi MM Schneerson had assumed the leadership, Rabbi Kramer went in for yechidus and requested a blessing on behalf of an acquaintance, but received no response. He kept asking the Rebbe throughout the yeschidus, to no avail. Finally the the Rebbe asked him, “Why do you keep asking if I’m not answering?” Rabbi Kramer reminded the Rebbe how he had once told him “oif a Rebbe darf men nit rachmonus hobin” – that for a Rebbe one needn’t have mercy. The Rebbe smiled and answered, “Obir men darf nisht mehader zayn” (“but we needn’t be too zealous about this”).