But if he will at all redeem it. — Better, and if he wishes to redeem it, that is, the man himself who vowed it for the sanctuary. The estimate put upon the animal in question was intended for anyone who wished to purchase it, not excluding, however, the person who vowed it.
He shall add a fifth part. — Whilst anyone else could purchase the animal at the valuation put upon it by the priest, its former owner is to pay a fifth more than the valuation price. This was probably intended as a fine for taking back a thing which he promised to the Lord. For the way in which the fifth part was computed during the second Temple see Leviticus 5:16.