This question sounds like a half-remembered bit of Hemingway legend. The legend is that some friends bet Hemingway that he couldn't write an entire short story in six words (some versions say that the challenge was for ten words or fewer). As the story goes, he came up with this six-word short story, considered the shortest complete short story ever:
In which Hemingway short story is the saying, "Children's shoes for sale"?
"For sale: Baby shoes. Never used."
What makes this a "complete" short story? It contains all that a short story needs — though most of the elements are implied. The five important elements of a short story are characters, setting, plot, conflict, and theme, and these five elements are all represented here:
Characters: A woman and the man who got her pregnant.
Setting: This appears to be a newspaper ad, and a number of conclusions about the setting could be drawn by considering where and during what time period one would run a newspaper ad for a pair of baby shoes.
Plot: Obviously, the woman became pregnant. She began preparing for the baby's arrival, which is evident from the fact that she bought or was given some new baby shoes.
- Conflict: The fact that the baby shoes were never used indicates that the baby died either before or during birth — quite a conflict for a young mother-to-be.
Theme: The theme of this story is dealing with loss — specifically the loss of a child. Are the baby shoes kept as a reminder of the loss or in hope of having another child? Are they destroyed in a fit of anguished rage? No; they are put up for sale, giving us a glimpse of how the characters are dealing with the loss as well as some of the considerations that went into the decision to sell the shoes.
This six-word short story is repeatedly attributed to Ernest Hemingway, although no one has been able to prove that he actually wrote it. Hemingway scholars generally agree, though, that it isn't outside the realm of possibility, given Hemingway's history and style. Regardless, this shortest of short stories will live on in Hemingway lore.