As is known, two of the Mitteler Rebbe’s daughters married grandsons of Reb Levi Yitzchock of Berdiychov. The first Chassunah took place in the town of Zhlobin and is called The Zholbiner Chassunah.
Being that the Alter rebbe praised his son’s qualities, Reb Levi Yiotzchok asked the Alter Rebbe to instruct his son to lead the assembled in bentching.
When Reb Levi Yitzchok would lead the bentching, he often would often become so excited that his hands began shaking and a lot of the wine in the ‘becher’ would spill out.
He expected to see a similar expression of excitement by the Mitteler Rebbe, but how shocked he was when the Mitteler Rebbe picked up the becher and began benthching – not a drop of wine spilled. there was no outward sign of emotion, he bentched just as Reb Levi noticed ordinary Jews.
Turning to the Alter Rebbe, he asked in bewilderment, “Mechutan, where is his greatness?”
The Alter Rebbe replied, I write in Tanya that the mind controls the emotions of the heart. By me it is only the emotions of chitzonius of the heart. however, when the innermost part of my heart becomes excited, i cannot control it and one will notice an emotional expression.
However, by my son, he also controls the innermost part of pnimiyus of the heart, and therefore you don’t notice anything.