Is it permissible for my husband to have intercourse with me before the end of the ten days of my menstrual period, in exchange for expiation, knowing that I have five days during which I only see yellowish discharge, and the interval between two menstrual periods is sixteen days?

If the yellowish discharge is continuous with menstruation, it is considered part of it. However, if it appears after purification (ṭuhūr), it is not considered anything. Yellowish discharge before menstruation that is accompanied by menstrual pains is considered menstruation; otherwise, it is not. Purification occurs either by the white discharge (al-qaṣṣah al-bayḍā’) or by the dryness of the spot.

It is forbidden for a husband to have intercourse with his wife during her menstrual period, based on the Almighty's saying: (And they ask you about menstruation. Say, "It is a discomfort, so keep away from women during menstruation") until they purify and bathe. A severe warning has been issued for anyone who has intercourse with a menstruating woman. A husband may enjoy his menstruating wife in ways other than intercourse. The wife must refuse to consent to intercourse during menstruation.