What is the recommended timing for the Adhan (call to prayer)?

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It is recommended that the Adhan be called at the beginning of the prescribed time so that people are informed and prepare themselves for the prayer. Bilal, may Allah be pleased with him, did not delay the Adhan beyond the time, though he sometimes delayed the Iqamah slightly. It is reported that Bilal would call the Adhan when the sun declined and would not call the Iqamah until the Prophet, peace be upon him, emerged, at which point he would call the Iqamah upon seeing him.