Restriction of Mapping to Small Class is Small

Theorem
Let $F$ be a mapping.

Let $A$ be a small class.

Then the restriction $F \restriction A$ is a small class.

Proof
The domain of $F \restriction A$ is a subset of $A$.

By Axiom of Subsets Equivalents, the domain is a small class.

By Mapping is Small, it follows that $F \restriction A$ is a small class.