Date: 21 Teves 5571
From: Rabbi Moshe Sofer
To: Rabbi Akiva
Rabbi Akiva challenges Tosfos's comparison between one who blows shofar for others after fulfilling his own obligation and a Kohen who repeats Birkas Kohanim. The Chasam Sofer defends Tosfos, arguing that arvus (mutual guarantorship) makes the shofar blower still personally obligated.
Source: Shu"t Chasam Sofer OC §167