Unto the Fourth Generation is a short story by Isaac Asimov.
A standalone story with minimal speculative elements, it was first published in the April 1959 issue of The Magazine of Fantasy and Science Fiction. It was later collected in 1969's Nightfall and Other Stories.
Summary[]
Samuel Marten, a 23-year-old junior executive, becomes distracted on his way to a business meeting when he sees a truck with the name "Lewkowitz and Sons." He unconsciously alters the name to "Levkovich" and becomes increasingly preoccupied with variations of the name he encounters. This preoccupation causes his business meeting to go poorly.
After the meeting, he wanders through New York City, following a trail of similar names like Lefkowitz and Levkowitz, which leads him to Central Park. There, he meets an old man named Phinehas Levkovich, who is dressed in outdated clothing. The old man is on his deathbed and reveals he was born in Czarist Russia. After the deaths of his wife and sons, his daughter Leah emigrated to America. He has prayed to meet a descendant from her line.
Samuel Marten realizes he is that descendant—Leah's daughter's daughter's son, the first son born into the family. He asks for and receives the old man's blessing, who says, "I go now to my fathers in peace, my son."
Immediately following this, time reverts to two hours earlier. Marten is once again on his way to his business meeting, now free of anxiety and with an unexplained certainty that everything will be well.