How should I deal with the whispers of the devil with regard to ablution and purity?
Whispers in ablution are from the devil, and so you should take refuge in Allah from the devil`s evil suggestions that aim to distort the religion. Thus, once an organ is completely pure, don`t question its purity since having whispers doesn`t mean that the purity is invalid as it has already been established.
Should one who doesn`t perform prayer out of laziness make it up later, and how should he/she do so?
All perfect praise be to Allah,The Lord of The Worlds He/she is obliged to make up missed prayers by offering with each obligatory prayer another one, and if he/she offers two, then it is better. And Allah Knows Best.
What is the ruling on performing dry ablution (tayammum) instead of the ritual bath due to severe cold?
Whoever is sick such that he cannot use water, or finds the water cold and heating it is not possible, and the person would be harmed by using cold water, it is permissible for him to perform tayammum. He must make up what he prayed with tayammum, because this is a place where there is water. And Allah the Almighty knows best.
Does the use of suppositories, enemas, or hemorrhoid creams affect the validity of fasting?
Enemas and suppositories inserted through either of the two private passages invalidate the fast. This ruling is based on the statement of Ibn Abbas (may Allah be pleased with him): "Breaking the fast occurs from what enters (the body), not from what exits." [Reported by Al-Bayhaqi in As-Sunan Al-Kubra]
His generalization regarding anything entering the body indicates that it invalidates fasting, whether it is nutritious or not, as even non-nutritious substances resemble food in form.
It is recommended to use them before Fajr or after Iftar. However, if a person must use them while fasting, they should continue refraining from food and drink for the rest of the day and make up for that day later.
