Answered by Shaykh Amjad Rasheed
Is a woman’s prayer valid if she prays with her feet uncovered?
In our school, covering a woman’s feet during the prayer is obligatory; if she does not, her prayer is then invalid. If just a part of her feet is uncovered, as is common with many women today, she must still repeat those prayers.
But to avoid making up the prayers, one could follow the opinion of those who say that the prayer is valid with the feet uncovered, and that is the opinion of Imam al-Muzni amongst our Shafi’i scholars and this is the famous position of the Hanafi school. However, to make up the prayers is best [f: i.e. recommended, though not obligatory].
– Amjad Rasheed
(Translated by Shazia Ahmad)