And if [it be] of an unclean beast
This is to be understood, not of the firstling of unclean creatures in common, which were to be redeemed with a lamb, and not with money, according to the estimation of the priest, and a fifth part added to that; but of such as were sanctified, or vowed, for the reparation of the sanctuary, as Jarchi notes:
then he shall redeem [it] according to thine estimation;
the price the priest should set upon it, how much it was worth in his judgment:
and shall add a fifth [part] of it thereto;
to the price, set upon a fifth part of that over and above the sum; this the sanctifier, or he that made the vow, was obliged to pay, if he thought fit to redeem it:
or if it be not redeemed;
by him, he does not choose to give the price, and the fifth part:
then it shall be sold according to thy estimation;
to another man, without the fifth part, that chooses to purchase it, and then the purchase money was laid out for sacred uses.
The Brenton translation of the Septuagint is in the public domain.