They are slaughtering an animal and a person passes by them. He guesses that some blood has been sprinkled on his clothes but he does not investigate. After prayer, he comes to know that the amount of blood is more than the exempted one. Is his prayer valid?
In the following issue, do you mean obligatory caution or mustaḥabb one? If one guesses (more than fifty percent) about the number of prostrations or rukū‘, he should – by caution perform prostration/rukū‘ again and say the prayer again as well.
When the prayer leader is in rukū‘, assuming a ma’mūm joins the prayer, recites the takbīrah al-iḥrām but, then, fails to enter the state of rukū‘ with the prayer leader, what becomes of the ma‘mūm‘s duty thereafter?
It is said that when imam is in the last tashahhud, one may start – in order to reap its reward - the congregational prayer, sit down and say tashahhud. What is meant by to sit down, is it normal sitting or tajāfī?