Shevuos 2:3-4

Shevuos 2:3

Let’s say that someone was rendered ritually unclean while he was in the Temple courtyard. Later, he (a) forgot about this impurity but he was aware that he was in the Temple, (b) forgot that he was in the Temple but was aware of his impurity, or (c) he forgot about both things. If he prostrated himself in the Temple, remained in the Temple long enough to prostrate, or exited via a longer route, he is liable for impurity in the Temple; if he immediately exited via the shortest route, he is not liable. This is the positive mitzvah regarding the Temple (to send an impure person out of the camp) for which they (the court) are not liable (if they make an erroneous ruling).

Shevuos 2:4

There is a positive mitzvah regarding a menstruant woman for which the court is liable (if they make an erroneous ruling): if, during the course of marital relations, a woman informs her husband that she has become ritually unclean, if he withdraws immediately (i.e., while still physically aroused), he is liable because withdrawal in that state is also pleasurable.