Selling a Torah scroll for the sake of Pidyon Shvuyin:<a href="#_ftn1" name="_ftnref1">[1]</a>
It is permitted for one to even sell a Torah scroll for the sake of redeeming a captive, [even though in general it is forbidden for one to sell a Torah scroll unless one needs the money to get married or study Torah<a href="#_ftn2" name="_ftnref2">[2]</a>].
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<a href="#_ftnref1" name="_ftn1">[1]</a> Rama 270:1; Shach 252:1; Taz 252:1; Beis Yosef 252; Tosafus Megillah 27a; M”B 153:24
Other opinions: Some Poskim rule that one may not sell a Torah scroll for the sake of redeeming a captive. [Derisha 252:2, brought and negated in Shach and Taz ibid]
<a href="#_ftnref2" name="_ftn2">[2]</a> Megillah 27a

Shulchan Aruch HaRav | Selling a Torah scroll for the sake of Pidyon Shvuyin

Selling a Torah scroll for the sake of Pidyon Shvuyin:[1] It is permitted for one to even sell a Torah scroll for the sake of redeeming a captive