Torah Temimah cites Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10) · R’ Yehudah.
Sefaria — Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10)
“And he shall bring” — R’ Yehudah says: a mitzvah is precious in its time. He brings immediately; we do not make him wait until he becomes rich.
Diyuk of “ve-hevi” favoring immediate performance — a mitzvah is precious in its time.
A poor man’s flour-chatas is accepted at once. The court does not require him to postpone in hope of a higher tier. The mitzvah’s value lies in its timely performance; delay for the sake of a more expensive offering is not demanded.