Reference: Sharh ‘Umdatil-Fiqh – Tape No.8, Question No.9
Question: Whilst the iqaamah is being called, when is it legislated to stand for the prayer? Is it when a specific word is uttered?
Response: They say it is recommended to stand [for the prayer] when the mu.adhdhin says the words:
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…however, I do not know of any evidence for this.
So [whilst the iqaamah is being called], he should stand [for the prayer] when he is ready, whereas some of them say [he should stand] when he sees the imaam stand [for the prayer].