פירוש על מגילה 26:7

And immerse due to cleanliness, such that she should not be disgusting to the righteous one from the semen of Ahasuerus.

And immerse and sit in the lap of Mordecai: But perhaps you will say, "Behold there was no distinction of three months (an interval to determine the paternity of a child). As behold, that evil man was found with her every day." But it can be said (answered) that she would have intercourse with a sponge [as birth control].