What is the ruling on the prayer of one who is unable to prostrate due to knee pain, and is it permissible for her to pray sitting, and is it permissible for her to hold the Mus'haf and read from it during prayer?

If the worshipper is able to stand during prayer, and the pain during prostration is bearable, then she must stand and prostrate on the seven limbs.

If the pain is severe and unbearable, then she prays standing and bows, then sits on the ground or a chair, and gestures for prostration with her head. Her gesturing is done when she is unable to prostrate.

It is advised to disregard the whispers of Satan.

There is no harm in holding the Mushaf (Qur'an) and reading from it during prayer.