Does the unintentional exposure of part of a woman's foot invalidate the prayer?

Question:
She asks: If part of a woman's foot is unintentionally exposed from under her abaya or sheet, does this invalidate her prayer and require her to repeat it, or not?

Answer:
If something of her foot is exposed and becomes visible where people can see it, if there is anyone present with her, her prayer is invalid; because part of her 'awrah (the part of the body that must be covered) has been exposed. This is unless it is a small amount, or if it is a large amount but she covered it. If a large amount or a small amount is exposed and she leaves it uncovered, her prayer is invalid. However, if she hastens to cover it, her prayer is valid. Yes. Praise be to Allah.