The Rabbis taught, in Chullin 94a, a cluster of warnings about the small deceptions that undo a household. None is dramatic. Each is deadly.
The shoe. Do not sell a neighbor shoes made from a beast that died of disease as if the hide were from a properly slaughtered animal. The leather is weaker. Worse — the beast may have been bitten by a serpent, and the venom lingering in the skin may kill the wearer.
The cask. Do not send a neighbor a barrel of wine with a thin skim of oil floating on top to make it look like a barrel of oil. It once happened that a man received such a cask and, believing it was oil, invited guests to a feast built around that single ingredient. When the guests arrived and the deception came to light, the host had nothing worthy to serve. Shamed past bearing, he went out and took his own life.
The guest. Do not give anything from the table to the host's child unless the host permits it. In a time of scarcity a man invited three friends to share three eggs. His son wandered into the room. One guest gave the boy his share. The other two did the same. The father returned to find his child with both hands and mouth full of eggs meant for guests — and struck him down in fury. The boy died instantly. The mother, seeing this, threw herself from the roof. The father followed her. Rabbi Eliezar ben Yacob closes the story: three souls of Israel perished in that affair.
A small lie in a barrel, a small kindness at a table — the weight of what we do for and to each other is never small.