Regarding the issue of double intention in fasting, we’d like to make it clear that it has different forms. One of which is making double intention in Ramadan fasting, while the other is ma king double intention in optional fasting like the six days of Shawwal.
The example of double intention in Ramadan fasting includes intending to fast the obligatory fast of Ramadan as well as other optional or obligatory fast like fasting for a vow. On this form, Muslim jurists assert that the month of Ramadan is exclusive for its obligatory fasting; thus, one cannot combine the intention of the obligatory fasting of Ramadan with any other types of fasting.
Given the above, it is not valid to make double intention in Ramadan fasting for it is exclusive to its obligatory fast.
In this regard, Imam Al-Sarkhasi says in Al-Mabsoot: “When the Sharia designated the obligatory fasting of Ramadan, it negated all other forms of fasting during it (referring to Ramadan).” Al-Sarkhasi also cites what Imam Zufar (student of Imam Abu Hanifah) said in respect to fasting Ramadan with the intention of recommended fasting: “What is permitted during Ramadan is only one type of fasting [that is the obligatory fasting].”
As for making double intention in the optional fast, some scholars allow it while some others do not.
