My Brothers: The invalidators that we talked about in the fourteenth majlis with the exception of menstruation, do not invalidate the fast under three conditions.
The first condition: If a person is ignorant, then their fast is not invalid.
This is because the verse, “Our Lord do not hold us responsible if we forget or fall into error.” Allah said pertaining to this verse, “I have done so.” (Muslim) As well as the verse, “But there is no blame on you if ye make a mistake therein: (what counts is) the intention of your hearts: and Allah is Oft-Returning, Most Merciful.”
Regardless if the person is ignorant to the Shari’ah thinking that this act does not invalidate the fast. Or if they are ignorant of the situation or the time. For example if someone thinks that Fajr hasn’t arrived yet and they continue to eat, or if they think the sun has set and they begin to eat. All of these situations do not invalidate the fast.
As is related in the Saheehayn ‘Adi b. Hatim (RA) reported that when this verse was revealed, “Until the white thread of dawn appears to you distinct from the black thread.” Adi b. Hatim said, “Messenger of Allah (SAW), verily I keep underneath my pillow two strings, one white and the other black, by which I distinguish night from dawn.” Upon this the Messenger of Allah (SAW) said, “Your pillow seems to be very wide! For the word khait (string, thread) implies the blackness of the night and the whiteness of the dawn!” ‘Adi did eat after the time of Fajr came, and the Prophet (SAW) did not order him to make up the fast.
Also on the authority of Asma’a bint Abi Bakr (RA) that she said, “We broke our fast during the time of the Messenger (SAW) while it was cloudy, then the sun became visible to us, and I do not recall the Prophet (SAW) ordering us to make the day up.” (Bukhari)
Similarly, if you break the fast after the time for Fajr approaches, and you think it is still before Fajr, then you find out that the time for Fajr has already approached, then your fast is still valid. You do not have to make up the fast, because you were ignorant of the time. Once the person finds out that they should not be eating, then they should immediately stop eating and clean their mouth.
The second condition: If a person forgets and eats.
They also do not have to make the day up. The Prophet (SAW) said, “Whoever eats or drinks while they are fasting out of forgetfulness, then they should continue fasting, for indeed it is Allah who feed them and gave them to drink.” (Agreed upon)
Once they realize that they should be fasting, then they must stop eating and remove whatever they have in the mouth. It is obligatory on the person who sees a fasting person eating to remind them as Allah says in the Qur’an, “And help each other on goodness and taqwah.”
The third condition: If someone is forced to eat.
Their fast is still valid and they are not responsible for making the day up. Allah (SWT) says, “Any one who, after accepting faith in Allah, utters Unbelief,- except under compulsion, his heart remaining firm in Faith – but such as open their breast to Unbelief, on them is Wrath from Allah, and theirs will be a dreadful Penalty.”
So if Allah pardons the ruling of kufr on who is forced, than the ruling of other things should be the same as well. As the Prophet (SAW) said, “Indeed Allah pardons for my Ummah mistakes, forgetfulness, and compulsion.” (Ibn Majah, Bahaqi)
The fast is not invalidated by kohl, or medicine for the eyes, even if they can taste it in their throat, because it is not intended as a food or drink. Likewise medicine in the ears and on cuts do not invalidate the fast.
If you taste the food and don’t swallow it, or if you smell food, then your fast is still valid. The scent of incense will not break the fast either, but they should not exaggerate with inhaling the smoke.
Using the miswak will not break the fast either. In fact, it is recommended to be used especially in the begging and the end of the day.
It is also permissible to cool yourself off with water while you are fasting. It is narrated that the Prophet (SAW) used to poor water on his head while fasting from thirst or from the heat. Ibn Umar (RA) soaked his clothes and then wore them while fasting.