Salaah

Q: As far as I am aware, speaking intentionally or unintentionally will nullify the salaah and it will have to be re-prayed again according to the hanafi maddhab (although, if I am incorrect in my understanding then please correct me jazak Allah khayr). The question I would like to ask is that say for example, if I recite اَللَّهُمَّ رَ‌بَّنَا آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الْآخِرَ‌ةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ‌ and in my heart I say Aameen but my tongue may move slightly unintentionally, however there is no sound of any letters coming out, can that be classed as speaking in Salaah?

Q: When we say the Kalimah Laa Ilaha ILLAllah Muhammadur Rasulullah, then can we also say La Ilaha ILLAllah Muhammadun Rasulullah? With the nūn? Because in my local masjid there used to be a muezzin who used to say Ashadu Anna Muhammadun Rasulullah or Muhammadan Rasulullah, and the Imam said he was wrong and it should be said as Muhammadur Rasulullah.

Q: Are hanafi ladies supposed to cover the area between the throat and chin which normally remains exposed with a normal burqa? Normally some people have a double chin in that area. The Malaysian and Thailand girls of our Madrassah who were shafi'i would wear a special burqa to cover that part.

Q: I have an aged grandmother who has been diagnosed with alzheimer's disease. Unfortunately, her condition has deteriorated to such an extent that she forgets many things. Her salaah is one of the things that she is constantly confused about. She performs Salaah at incorrect times, says she read it when she hadn't read it and mixes up the salaahs. She also forgets to perform wudhu, sometimes performs it incorrectly, and at time makes tayamum. We try to correct her and guide her, but sometimes it is impossible. What is the correct ruling in this regard?

Q: If I carry out my fard salaah and later after the time where the salaah is valid, find out that I did an action that would have invalidated the salaah, is it sufficient for me to not repeat that mistake in all future prayers or must I make up the salaahs that I unknowingly carried out the mistake in?

Q:

1. If a person reads the ruku tasbeeh in sajda and due to the mistake he makes a sajda sahwa, is the salah valid?

2. How many sajda tasbeehs can a person read in tahajjud salaah?

Q: If an imam recites the 1st 15 verses (i.e. 1st ruku) from (1-15) of Surah Maryam in his 1st rakaat of fajr salah and in his second rakat recites 25 verses (i.e 2nd ruku) from 16-40, is the salaah valid?

Q: Does reciting a short letter long (like kawthar as kawthaar), and a long letter short (like 'alaa reading as 'ala) invalidate the salaah if it is done on purpose?

Q: Is a person allowed to skip one surah in namaaz?

Q: During jalsa, would it make my salaah invalid according to the hanafi madhab if I were to recite the dua 'Allahuma aghfirlii wa arhamnee?