Is using a shirt (Qamees) and a loincloth (Mee'zar) alongside the main shroud permissible?
General Chapter
Al-Mughni
Book of Funerals
Primary text
Shrouding in a shirt, a loincloth, and the main shroud (Lafaafa) is not disliked, although the configuration involving the finest three layers is preferred. This method is permissible; the Prophet (peace be upon him) clothed Abdullah ibn Abi with his own shirt when he died, as narrated by Al-Bukhari. Thus, the deceased may wear the loincloth, then the shirt, and then be wrapped in the final shroud.
Supporting text
Imam Ahmad prefers that if a shirt is used, it should resemble the shirt of a living person, having sleeves, openings, and buttons, but the shirt should not be buttoned up.