It is mandatory to say it.

Is it obligatory to say “Rabbi ighfirli” between the two prostrations in each Rakah of Salaah?

Prayer | March 26, 2014 10:25 am
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If a sutra is placed infront of a person (who is praying) in such a way that it is not exactly at his place of prostration, but rather a bit to his right or to his left, will that be counted as a sutra?
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What is the approximate duration of time that the Zuhr prayer lasts? Suppose it begins at 11 30 am, at what time would it end?