成唯識論演祕 2.143

2.143

按彼論第三云：然色聚有分非極微，何以故？由極微即是分，此是聚色所有，非極微復有餘極微，是故極微非有分也。

According to fascicle three of that treatise: However, an aggregate of matter has parts, but an atom does not. Why? Because the atom is itself a part; this belongs to aggregated matter, and there are no further atoms beyond the atom; therefore, an atom does not have parts.