Date: 5 Tevet 5594
From: Rabbi Moshe Sofer, Frankfurt am Main
To: Rabbi Meir
The responsum advises a person who vowed to study Mishnayot by heart, but found it interfered with his regular studies, that he should seek annulment of the vow to allow him to return to his usual learning, as the annulment would not negate his past efforts.
Source: Shu"t Chasam Sofer Collected §45