Is it permissible to wear an Ihram garment consisting of three pieces, where an unstitched cover for the 'awrah is added beneath the two upper and lower pieces? And is expiation required if one wears it?

The fundamental principle is that a pilgrim in a state of ihram may wear whatever they wish, except for what the Sharia has explicitly prohibited. This includes anything tailored to fit a specific limb or the entire body, which is known as "stitched clothing" (al-makheet), and clothing that has perfume on it. The Prophet, peace and blessings be upon him, mentioned what a pilgrim in ihram should not wear: "A pilgrim in ihram should not wear a shirt, trousers, a burnous, or slippers, unless he cannot find sandals, in which case he may wear what is below the ankles. Nor should he wear any garment that has been touched by saffron or wars." "Stitched clothing" (al-makheet) according to jurists is anything sewn to the measure of a limb or the entire body, such as a shirt or trousers. A piece of cloth wrapped around the body to cover the private parts is permissible because it resembles an izar (lower garment) and is not tailored to fit a specific limb.