When the father knew that he has correspondence and he corresponded to his son in all physical features, he was able to finally find him in the lost city.
He had been looking for his son for twenty years and when he found his son through correspondence, and he was so happy and delighted, he vowed and promised his son that he will take care of him throughout his life and they were united again.
This was all because of destiny and when people are destined to meet, nothing can stop them from meeting.
Image is from the prompt.