From: Rabbi Moshe Sofer
To: Rabbi Ber
A man died leaving sefarim inscribed as purchased with ma'aser money, with an obligation to lend them during his lifetime. The Chasam Sofer permits the guardians of the impoverished orphans to sell the books, ruling on multiple grounds: ma'aser must go to the poor and the relatives' conditions are not binding once funds were transferred; the lending obligation was personal and lapsed at death; heirs are not bound by their father's vows; and the inscription on the books, never verbally declared, likely does not constitute a valid neder.
Source: Shu"t Chasam Sofer YD §232