Can he be alone with a woman to lead her in prayer?

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Check below answers in case you are looking for other related questions:
Is it permissible for a Muslim man to give accommodation to a man who is a stranger or to host him in the marital home?
If the imam says Qunoot in Fajr prayer silently, should he say Qunoot or remain silent?

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Related Answers:
Is it valid to pray behind one who makes grammatical mistakes when he recites Qur’aan?
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Is it permissible for a Muslim man to give accommodation to a man who is a stranger or to host him in the marital home?
If the imam says Qunoot in Fajr prayer silently, should he say Qunoot or remain silent?

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