QuestionIn fasting the six days of Shawwal is it necessary that the days be consecutive or is there no harm in fasting them separately (spread out) during the month? Answer
Fasting six days of Shawwal is a confirmed Sunnah from the Messenger of Allah (Sallallahu Alayhi wa Sallam). It is permissible to fast them consecutively and separately. This is because the Messenger (Sallallahu Alayhi wa Sallam) mentioned their fast unrestrictedly and he did not mention that they should be done consecutively or separated. This was when he said: "Whoever fasts Ramadhan, and then follows it up with six (days of fasting) from Shawwal, then that is as if he fasted the entire time (i.e. year) (Muslim no 1164)
This was recorded by Imam Muslim in his Sahih. And success is from Allah.
Shaikh Ibn Baz (Rahimahullah)
Reference: Fatawa Islamiyah Volume 3 Pages 335-336