The Rulings of Prayer: Dress Code Part 2
Women are to observe full hijab while performing their prayer like a pearl in the oyster shell.
It is befitting that they wear a chador while performing prayer
Performing prayers without chador or with a transparent chador is permissible only if one has observed full hijab beneath the chador meaning that the entire body except for the face, hands down to the wrist and feet down to the ankles has been covered, also the clothes should not be too tight or transparent to reveal the shape of the body.
However, if a lady was unaware of this ruling and thus she has been performing their prayers without wearing a proper chador or observing full hijab, their past prayers are valid as long as they were not negligent in learning the related religious rulings.
In addition to all this, covering all jewels and ornament, even a wig, is obligatory while performing prayers even if a non-mahram is not present. It is not necessary, however, to cover rings while praying. In the case that a lady was unaware of this ruling and thus have not been covering their ornaments during prayer, their prayers are valid.
All men and women must observe the necessary dress code in all obligatory prayers, including Iḥtiyāṭ prayer as well as while performing Sahw prostration, Qaḍa prostration or Qaḍa Tashahhud.
However, while performing obligatory prostration outside of prayer such as obligatory prostration for certain verses of the Quran, it is not obligatory to observe hijab if there is no non-Mahram present.