The financial situation in Yeshivat Tomchei Temimim-Lubavitch was very difficult. There was never enough food for the students let alone money for other necessities. One of the directors of the yeshiva approached a very wealthy Jew in Rostov and asked him for help.
At first the man refused, but after much prodding he finally agreed to contribute some of the much-needed funds. He would give the money, however, on one condition: He and his wife had been married for many years and still had no children. If the rabbi would promise them a son, the man would help the yeshiva. The yeshiva desperately needed the money. The rabbi promised the wealthy man that in the merit of his tzedaka (charity) he would have a son. The man gave the money and the crisis lessened.
A year passed but no celebration for the birth of a child took place in the wealthy man's house. He went to the director of the yeshiva and said, "You promised me a child. I kept my part of the deal but you haven't kept yours." The rabbi encouraged the man to have faith and to wait patiently. He was certain that in the merit of the tzedaka the couple would have a child.
Another year passed and still no child was born. This time the wealthy man approached the rabbi angrily. "You deceived me. You promised me a child and we do not have any children!"
The rabbi went to the Rebbe, Rabbi Yosef Yitzchak, and told him the whole story. "Who told you that you could promise someone that they will be blessed with children when you cannot keep your word?"
"But Rebbe," the rabbi replied, "the yeshiva was in dire straites and I was certain that in the merit of his donation that would enable hundreds of students to study Torah that he and his wife would be blessed with a child."
"Still," said the Rebbe, "it is forbidden to make a promise that you cannot personally keep."
A couple of years passed. The man began harassing the rabbi on a daily basis. Day after day he confronted him, crying bitterly, "Where is the child you promised me?"
The rabbi again went to the Rebbe. "He will not leave me alone. He does not let me live," the rabbi told the Rebbe.
"Go to the man," said the Rebbe, "and tell him in my name that he will have a child this year. And never again make a promise that you can't keep."
The following year the man and his wife made a festive celebration upon the brit mila (circumcision) of their son.
