Reb Groinem, the mashpia, recounted that an agunah with an eight - or nine-year-old mute son came to the Tzemach Tzedek in Lubavitch and would constantly badger the Rebbe to tell her husband’s whereabouts. On one occasion she directed her son to pull the edge of the Rebbe’s garment to catch his attention. “Tell your mother that your father is returning soon, ” the Rebbe told the boy. The child repeated the message to his mother.
When they told the Tzemach Tzedek of the miracle, he answered, “I didn’t know that the boy was mute. ”