As I Heard Them, Vol. 1, pp. 156-157, no. 33
The same young man came to the Rebbe for yechidus one summer day in the large zal (study hall) in Rostov. The Rebbe’s face was radiant. “I am accustomed to sing while davening,” he had said. “Would it be better to hold myself back?”
“No, no, ” answered the Rebbe, “these are the G-dly soul’s powers revealing themselves. ”