Questioner: With regard to, my dear brother, fasting the six days of Shawwāl, on occasion, I have broken [my] fast [on] one of the days of the Ramaḍan that comes before Shawwāl and wanted to fast the six days of Shawwāl.
Is it permissible for me to make my intention a making up [of the missed Ramaḍan fast] and a fasting of one of these six days at the same time?
Shaikh Al-Albānī: If you were asking about the permissibility, then the answer is: yes, it is permissible. And I’m going to now mention to you here three levels; after that, a Muslim chooses from them that which he likes.
The first level, and it is the highest, is that he fasts the make up separately and [the] Shawwāl separately. Why? Because we know that a good deed is [rewarded] with 10 times the like of itself. So when he fasts a day from Ramaḍan, for [that], at the very least, is [the reward of] ten [similar] good deeds; and [when] he fasts a day from Shawwāl, for Shawwāl there is [the reward of] ten [similar] good deeds. [Totaled together,] they become 20. This is the best situation, at the highest level.
The second situation is [where] he isn’t prepared, doesn’t have time, doesn’t have the energy, for one reason or another. He wants to fast a day from those that are upon him [to make up], for example, or six days from those that are upon him from Ramaḍan [to make up], and [at the same time] he wants to cover over [the same days] the six [days] of Shawwāl. This is the second level.
We say: He is to make the intention to make up from that which is upon him from Ramaḍan, and carry out [that intention]. And he is to attach to this intention an intention [to fast from] the six days of Shawwāl.
This [person] gets recorded for him ten plus one [rewards]; the one [reward] is [for] that good intention [that wasn’t actually acted upon], based on his saying [ﷺ] in the ḥadīth qudsī: “When my slave thinks about doing a good deed and then does not do it, record it as one good deed for him, and if he does it, record it as ten good deeds for him,” up to 100 good deeds, up to 700, up to many times over that, and Allāh multiplies [the reward] for whomever He wills.
This is the second level: at the very least, [the reward of] 11 [eleven] good deeds is recorded for him.
The third and final level: he only fasts from that which is upon him. He doesn’t form [any intention] for the six [days] of Shawwāl at the same time, or maybe he doesn’t know he’s in the month of Shawwāl, as is the case with many among the Westernized Arabs.
Questioner: Clear. May Allāh grant you a good reward.
Silsilah Al-Hudá wa-l-Nūr, 327. 00:33:17
N.B.: Title and bold mine (Trans.)