He shall also, before entering upon the duties of his office, take and subscribe the oath or affirmation prescribed by Section 3, Article XIII of the Constitution which shall be filed in the office of the county clerk of his county.
55 ILCS 5/3-3005
Oath
P.A. 86-962.
Official source: Illinois General Assembly. Reproduced from public-domain Illinois statutes; confirm against the official source for the current text. Not legal advice.