Parashas Metzora · Passuk 15:24
Chabad.org — English translation + Rashi
Torah Temima points to Chazal (Chizkiyah; Niddah context).
English: “And her niddah shall be upon him” — it was taught: From where [do we know] that one who was intimate with a pure woman who then said “I have become impure” should not withdraw immediately? Chizkiyah said: Scripture says “and her niddah shall be upon him” — even at the time of her niddah she shall be upon him [i.e., he remains close rather than withdrawing abruptly].
Halachah of non-abrupt withdrawal
Chazal derive a practical rule of sensitivity: if impurity becomes known during relations, withdrawal must not be sudden.