I finished fasting the month of Ramadan, however, I had six days I didn't fast because my period came to me. i infeuated to fast them in the Shawal, and the other six days the prophet Muhamed instructed us to fast in the month of Shawal. I was planning to fast 12 days. While I was making up the days, a friend told me that I didn't have to fast 12 days, that fasting only 6 days would make up for the whole 12 days. I should take it as fasting the six days I had to make up and the six days from the month of Shawal. I did as she said. Am I correct? Provid me with Haddith, and verses from the Quran. And thank you very much.

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.

You should first start by making up the missed obligatory days, then you may fast the six days of Shawwal as Sunnah. This is the best and most appropriate way. Allah says in a sacred Hadeeth “… and no slave has ever tried to get closer to Me (Allah) by anything better than by what I have prescribed on him”.

This is why some scholars are of the view that it is disliked to fast optional fasting before making up any missed days even if there is time for that, like the 6 days of Shawwal. The Hambali School of jurisprudence is of the view that one has to first make up the missed days before fasting the Sunnah days. Their evidence is the following Hadeeth classified by Al-Anrna’oot  as a Dha’eef [weak] Hadeeth:

“Whoever fasts a voluntary fasting while some missed days of Ramadan are still due upon him, then his (voluntary) fasting is not accepted from him (i.e. is rejected) until he makes up the missed obligatory fasting."

As for combining the intention of two forms of worship at the same time, then some scholars are of the view that one gets only the reward of one of them. But the most prevailing opinion is the opinion of the Maaliki School of jurisprudence which states that the one who intends to do more than one act of worship at the same time gets the reward of all what he intended. The great scholar Lemrabott Ould Ahmad Zaidane said the following: “And does the person get the reward of a voluntary act he joined with an obligatory one? Apparently he does if there is proper intention.” The evidence for this is the Hadeeth: “The (reward of) deeds depend on intentions, and every person will get the reward of what he intended." [Al-Bukhari and Muslim]

And the Hadeeth "When a slave falls ill or travels, he gets exactly the same reward as the reward he gets for good deeds practiced at home when in good health.” [Al-Bukhari]

Therefore, the sick or traveling person gets the reward of any act he used to do in normal situation, let alone if a person performs a good act while having the intention of performing a voluntary act and an obligatory one at the same time, in which case, he gets the reward of fasting the missed days and the reward of fasting the Sunnah ones.

Hence, you will get, Allah willing, the reward of both fastings and you do not need to make the missed obligatory days again if you had a proper intention to make them up while fasting the six days of Shawwal as Sunnah.

Allah knows best.