Date: Erev Shabbos Kodesh, 2 Tammuz 5596
From: Rabbi Moshe Sofer
To: Rabbi Yitzchak Sofer
The Chasam Sofer defends the Rambam's interpretation that the Mishnah's case of 'the defendant said to them' refers to the defendant adjuring witnesses for his own defense, not for the plaintiff's benefit. Building on Tosfos' principle that the Mishnah lists definitive cases and the Tosfos Chadashim's reading of the slave case as a novelty about avdo k'gufo, the Chasam Sofer argues that the defendant case would be superfluous under the standard reading, compelling the Rambam's interpretation. He concludes that Shevuas HaEdus — derived from Shevuas HaPikadon — applies only when a plaintiff seeks to extract money, not when a defendant seeks to retain his possession.
Source: Shu"t Chasam Sofer CM §43