Jesus warns about causing a vulnerable believer to stumble by describing a great millstone hung around the offender's neck before being cast into deep water.
Jesus in Context
The Donkey Millstone
Jesus refers to a massive millstone of the type turned by animal power rather than a small household hand mill.
Introduction
Historical and Cultural Context
Grain could be ground with small hand mills, but larger mills used heavy stones turned by animal power. Matthew's expression refers specifically to a donkey millstone.
Why It Matters
The distinction matters because Jesus intentionally selects an enormous object. The exaggerated physical image communicates the severity of His warning.