Abelian real Lie algebra of dimension 3

The 3-dimensional abelian real Lie algebra is $\mathbb R^{3}$ with its usual vector-space operations and identically zero bracket:

[x,y]=0\qquad\text{for all }x,y.

Morphisms

Every real-linear map to another abelian real Lie algebra preserves the bracket. Hence endomorphisms form $M_{3}(\mathbb R)$ and automorphisms are the invertible matrices. A homomorphism from an arbitrary Lie algebra to this object must kill every commutator.