Leviticus 27:27
And if it be of an unclean beast, then he shall redeem it according to thine estimation, and shall add a fifth part of it thereto: or if it be not redeemed, then it shall be sold according to thy estimation.
Cross-reference
Leviticus 27:11–13
Parallel
Leviticus 27:11-13 gives the general rule for valuing and redeeming unclean animals; verse 27 applies that same procedure with a fifth.
Leviticus 5:16
Related theme
Leviticus 5:16 also requires adding a fifth, but for restitution of holy things—a different context than redeeming an unclean animal.
Numbers 18:15
Parallel
Numbers 18:15 commands redemption of firstborn unclean animals; Leviticus 27:27 adds a fifth when such an animal is dedicated and redeemed.