Leviticus 27:15

And if he that sanctified it will redeem his house. — Though the net price thus fixed by the priest is all that anyone else who wishes to buy it has to pay for the house, yet if the former owner of it, or, according to the practice which obtained during the second Temple, his son, wife, or nearest of kin, wishes to redeem it, he is to add one-fifth more than the valuation price, just as in the case of animals, and for the same reason, that is, for taking back a thing which he once promised to the Lord. (See Leviticus 27:13.)