An Etymological Dictionary of the German Language/Annotated/Musteil
Musteil, masculine and neuter, allied to Mus (Gemüse), “half the stock of provisions left on the death of a husband, and what remains thirty days later when an inventory is made; one half belongs to the widow and the other to the heirs” (Lessing); the share of the widow is called Musteil. Even in Middle High German (in the Middle German of the Saxon Code) musteile for *muosteile occurs.