Both a compensatory fast and the fasting of oath expiation are due on me. At the same time, I have the power to fast, and I wish to fast like the fasting of Prophet Dawood (David), may Allah exalt his mention. In the days that I fast, I like to combine the rewards of the compensatory and expiatory fasts in addition to the reward of the fast of Prophet Dawood, may Allah exalt his mention. Is this permissible? What should my intention of fasting be? I do not know the number of the days of compensation and oath expiation that are due on me.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If the compensation is to make up for an obligatory fast (like Ramadan), then it is obligatory. The expiatory fast is also obligatory. Fasting on alternate days like that of Prophet Daawood (David) is recommended (not obligatory). It is not valid to intend to observe an obligatory fast along with the intention of another obligatory fast – e.g. compensation and oath expiation – or to intend to observe an obligatory fast along with the intention of a voluntary fast –expiatory/compensatory and such optional fast as to fast every other day. One should, rather, fast a day for each: i.e. to fast for the compensation, then fast for the expiation, and then fast, if he so wishes, like the fasting of Daawood .

If you do not know the number of days that are due on you, then fast a number of days that you believe is most likely to be sufficient to free you from your liability.

Allah knows best.