Responsa for Bava Metzia 187:13

Q. B promised his young daughter in marriage to A's minor son. He gave A a written document obligating himself, from the time of the promise, to be A's debtor for 20^*In some sources (Pr. 50, L. 355) the reading is “marks.” The discrepancy arose because of the similarity of the two Hebrew letters of Khaf and Beth, which stand for 20 and 2 respectively. The Cremona source and the Mord., however, used the word Esrim, 20, specifically. marks should his daughter refuse to accept kiddushin from B's son when he will have arrived at his majority, or in case A himself should refuse to accept the kiddushin for his daughter. B died before A's son reached the age of 13, and his daughter married someone else. Now A demands the 20^*In some sources (Pr. 50, L. 355) the reading is “marks.” The discrepancy arose because of the similarity of the two Hebrew letters of Khaf and Beth, which stand for 20 and 2 respectively. The Cremona source and the Mord., however, used the word Esrim, 20, specifically. marks from B's heirs.
A. Since B has been prevented, by death, from fulfilling his promise, he never became obligated to pay the 20^*In some sources (Pr. 50, L. 355) the reading is “marks.” The discrepancy arose because of the similarity of the two Hebrew letters of Khaf and Beth, which stand for 20 and 2 respectively. The Cremona source and the Mord., however, used the word Esrim, 20, specifically. marks to A. Consequently his heirs owe nothing to A.
This question was also sent to R. Meir by his father, R. Baruch, who was one of the judges in this case.
SOURCES: Cr. 31; Pr. 50; Pr. 939; L. 355; Mord. B.M. 247; cf. Jacob Weil, Responsa 105; ibid. 142.