Actually, it's 61.153.
§ 61.153 Eligibility requirements: General.

To be eligible for an airline transport pilot certificate, a person must:
(a) Be at least 23 years of age;
(b) Be able to read, speak, write, and understand the English language. ...(c) Be of good moral character;
(d) Meet at least one of the following requirements:
(1) Holds a commercial pilot certificate with an instrument rating issued under this part;