Parashas Metzora · Passuk 15:17
Chabad.org — English translation + Rashi
Torah Temima points to Toras Kohanim.
English: “There shall be upon it shichvas zera” — it is said here shichvas zera and it is said there “with whom a man lies shichvas zera”: just as there [it must be] in its natural viable state, so here in its natural viable state.
Viable emission required
Chazal require that the emission on the garment still be in a state capable of fertilization; spoiled emission does not convey this impurity.