Method of Salaah

Tashahhud of Hazrat ibnu Masood (Radiyallahu Anhu)

Q: My question is that I've heard that it can be wrong to say assalamu 'alaika ayyuhan Nabiyuu because the prophet sallallahu alaihi wassalam has passed away and instead we should say al-salaam 'ala al-nabi as said by Ibn Masood in Sahih bukhari. Now, majority scholars say that we should not change tashahud after the death of prophet sallallahu alaihi wassalam but my question is Ibn Masood knows better than all of the current scholars because he was a sahaba so shouldn't we follow him because he knows better the prophet sallallahu alahi wassalam?

Another issue I have is that I came across a hadith where prophet sallallahu alaihi wassalam said that no supplication is accepted unless we send peace and blessings on him. I don't remember the source of this hadith so maybe you know. So can u tell me if it mandatory to send blessings on the prophet sallallahu alaihi wassalam every time we make dua and if we forget, that dua will be incomplete?

Pronouncing kaaf incorrectly

Q: I was reacting tashahud in the first sitting or last sitting (can't remember) of 4 rakat isha salah. I did not pronounce the small "kaaf" when I was reading "wa Rahmatullahi was barakatu" the kaaf of barakatu. So I went back to "wa Rahmatullahi" the recited from there till the end. Is my salah valid?

Raising the hands before ruku'

Q: My question regards the raising of the hands before and after ruku. I have read that there is not sufficient evidence to prove that Nabi (Sallallahu Alayhi Wasallam) did not perform this action during Salaah. The same applies to the positing of the hands during Qiyaam (on the chest or below the navel). I would be indebted if Mufti could please provide supporting evidence.