Father with baby is turned away by airline, but then he finds this letter in his pocket

At first, Ruben wanted to call the doctor who had arranged for everything in the hospital the day before. Maybe he knew a way to get around the airline’s regulations. But the airline worker was adamant: his daughter wouldn’t be allowed to fly until she was at least seven days old, no earlier. Ruben looked at the letter he had found in his pocket. “My last hope,” he thought. The letter had someone’s phone number that he had met earlier that day written on it. 

Who was it? You’ll read about it on the next page!