Deuteronomy 21:15-17

Webster_Strongs(i)
  15 H376 If a man H8147 shall have two H802 wives H259 , one H157 [H8803] beloved H259 , and another H8130 [H8803] hated H3205 [H8804] , and they have borne H1121 him children H157 [H8803] , both the beloved H8130 [H8803] and the hated H1060 ; and if the firstborn H1121 son H8146 be hers that was hated:
  16 H3117 Then it shall be, when H1121 he maketh his sons H5157 [H8687] to inherit H3201 [H8799] that which he hath, that he may H1121 not prefer the son H157 [H8803] of the beloved H1069 [H8763] firstborn H6440 before H1121 the son H8130 [H8803] of the hated H1060 , which is indeed the firstborn:
  17 H5234 [H8686] But he shall acknowledge H1121 the son H8130 [H8803] of the hated H1060 for the firstborn H5414 [H8800] , by giving H8147 him a double H6310 portion H4672 [H8735] of all that he hath H7225 : for he is the beginning H202 of his strength H4941 ; the right H1062 of the firstborn is his.