Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 72
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 72, with English translation by Maimonides (Rambam).
להקריב קרבן עולה ויורד, שנאמר: "ואם לא תגיע ידו" (ויקרא ה,ז), "ואם לא תשיג ידו" (ויקרא ה,יא).
To offer "the adjustable guilt offering" [as atonement for the violation of certain transgressions], as [Leviticus 5:1,11] states: "If his means are not sufficient.... If his means do not suffice...."