What is the ruling on a wife praying and having intercourse with her husband during the bleeding after a miscarriage, and what are the implications of that, given the differing opinions of jurists regarding whether it is nifas blood or not, and how is the financial expiation to be estimated?

The blood seen by the wife after a miscarriage is istiḥāḍah (irregular bleeding), unless human creation is discernible in it (the minimum period for this to be discernible is 80 days, typically 90 days). In the former case, she must pray, perform ablution for each prayer, and take precautions. Her husband is permitted to have intercourse with her. Any part of this blood that coincides with her regular monthly period is considered ḥayḍ (menstruation).

If the istiḥāḍah period included her usual days of menstruation, and the wife did not stop praying due to her ignorance, then she must make up those prayers (or, according to Shaykh al-Islām, she is not required to make them up due to her ignorance). Intercourse during istiḥāḍah is permissible, but it is forbidden if it coincides with the days of menstruation.

If the spouses were unaware of the menstruation occurring during that time, they do not owe any expiation. However, if the wife knew and concealed it from her husband, then she alone owes expiation, without the husband, according to those who deem it obligatory. There is no sin or expiation for someone who is forgetful, ignorant, or coerced, or if menstruation occurred during intercourse.

Expiation for intercourse during menstruation is only obligatory according to the Hanbalis, and it is one dinar or half a dinar of gold (approximately 4.25 grams of gold). The majority of scholars do not require expiation but only repentance.