In Petersburg, the highest officials in the land were drawing up evil decrees against the Jews of Russia. There was no time to waste, and so, ר‘ מנחם מענדל of Lubavitch (the צמח צדק ), sent his son ר‘ שמואל to Petersburg with orders to make sure the decree would not pass. ר‘ שמואל was the Rebbe's youngest son, yet it was ר‘ שמואל who was chosen for this important mission. But he did not travel alone. His older brother, ר‘ יהודה לייב , who was twenty years older than him came with him to the capital.
Before they set off on their journey ר‘ שמואל asked his brother one thing "I must insist upon one condition if we are to travel together. I must ask that you stop yourself from giving any ברכות along the journey. Our father is the Rebbe, and only he should be the one to give ברכות ."
ר‘ יהודה לייב was accustomed to giving ברכות to people; people always gathered around him wherever he went, asking for his help in serious matters of health, פרנסה or any of the other many problems that they had in those hard times. He was uncomfortable agreeing to his brother's wishes, but he had no choice. Keeping his word, however, wasn't so simple. People were used to receiving ר‘ יהודה לייב 's ברכות , and whenever people heard of his arrival, they gathered to meet him. Each person came with a different, very important need for רחמנות , and each sad story pierced ר‘ יהודה לייב 's kind, compassionate heart like an arrow.
In one village he met an especially persistent woman. Standing herself in front of ר‘ יהודה לייב , she begged him to give her a ברכה , crying, screaming and weeping. The heartbroken woman had no children, and she was determined not to move until ר‘ יהודה לייב blessed her with a child. ר‘ יהודה לייב was moved by her tears, but he had promised his brother, and so he refused to give a ברכה . He replied only, "Go to my father. He will surely give you a ברכה ." The woman refused to be put off, and her crying could be heard throughout the entire village. Finally, in utter desperation, he cried, "Go to my brother, perhaps he will give you a ברכה !"
Sure enough, she soon appeared before ר‘ שמואל . The same thing happened, but ר‘ שמואל insisted, "Go to my father, he will surely give you a ברכה ."
The woman continued her pitiful cries until, unable to listen any more, ר‘ שמואל turned to his brother and said, "Call the coachman so that we may leave this place!"
The driver jumped to his seat and urged the horses forward, but the wheels didn't budge. The woman had placed a stick in the wheel and the coach couldn’t move. Now ר‘ שמואל was fed up. He got down from the coach and told the woman, "Go eat a bagel!" - the equivalent of "Go fly a kite!". In a flash the annoying woman was gone and the two brothers continued in peace on their way to do their mission in Petersburg.
A year passed and the incident with the woman was long forgotten. In the mean time the צמח צדק had passed away, and ר‘ שמואל , the youngest of his seven sons, became Rebbe. One day a man arrived in Lubavitch and appeared before the new Rebbe holding two beautiful cakes.
"Last year you gave my wife a ברכה that she would have a child and she has just given birth. She has asked me to bring these cakes to the Rebbe to thank him for his ברכה ."
"Would you remind me of my meeting with your wife? I cannot remember that such an incident occurred last year."
"Well, my wife was in such and such a village and she begged you to give her a ברכה for a child. You told her, 'Go eat a bagel!' And Rebbe, my wife ran to do exactly what you told her."
"I am very happy to hear your good news. Tell me, though, why are you bringing me two cakes? Surely one would be thanks enough."
"Forgive me. I didn't tell you the whole story. You see, you told my wife to eat a bagel, but she was very anxious for your holy ברכה to be מקוים . And so, instead of one, she ate two bagels, just to be sure. And it worked, for she has just given birth to twins! And that is why she sent you two cakes," the happy father said.
Reb Shmuel was deeply moved by the man's words. "Know that there was a decree from שמים that you and your wife would never have children. Therefore, I was unable to promise her a child. It was just out of frustration that I told her to 'eat a bagel.' But because of her pure and simple faith in the ברכה of a צדיק the decree was annulled and you and your wife have been blessed with children."