And Ibn Abbas (may Allah be pleased with them both) said that there is no harm in observing them (the missed fasts) on separate days, because Allah’s command is only this:“Complete the count on other days.”And Sa‘id ibn al-Musayyib said that the ten days (of Dhu’l-Hijjah) are not better for the one upon whom the fasts of Ramadan are obligatory (and who has not yet made them up); rather, he should make up the Ramadan fasts first. And Ibrahim al-Nakha‘i said that if someone was negligent (in making up Ramadan fasts) and another Ramadan came, then he should fast both, and no fidya (compensation) is obligatory upon him. And from Abu Huraira (may Allah be pleased with him) this narration is mursal, and it is reported from Ibn Abbas (may Allah be pleased with them both) that he (should) also feed the poor. Allah, the Exalted, did not mention feeding (the poor) in the Qur’an, but only said that the count should be completed on other days.

Narrated `Aisha: Sometimes I missed some days of Ramadan, but could not fast in lieu of them except in the month of Sha'ban." Said Yahya, a sub-narrator, "She used to be busy serving the Prophet ."