TT #47 · Parshas Tazria · Aliyah 1 · Passuk 7
English: He shall offer it before GOD and make expiation on her behalf; she shall then be pure from her flow of blood. Such are the rituals concerning a woman who bears a child, male or female.
Chabad.org — Chumash, English translation + Rashi for Vayikra 12:7
Torah Temimah cites Sifra (Toras Kohanim) on “and he shall offer it” for the rule that, although two offerings are ordinarily required, both are not indispensable.
Sifra — Vayikra 12, Midrash Sefer
English: “And he shall offer it” — since two offerings are required, one might think both are indispensable. The wording “and he shall offer it” teaches that one offering is indispensable, but both are not indispensable.
Textual limitation
The first step establishes only that one of the pair must be brought; it leaves open which offering is indispensable. The following Sifra unit identifies the required one.