You did sin as this was mandatory for you to continue fasting. There

is no expiation. Only repent and ask Allah for forgiveness.

I just started fasting to make up one of my missed Ramadan fasts together with the Sunnah Monday fast. A little before Shurooq, my husband arrived after a 4-day Umrah trip and insisted on sex. He said it was a matter of my iman (even though I had chatted with him a few hours before and informed him of my intention to fast). Hence I broke my fast and we had sex. Did I sin? What is the expiation?

Fasting |