Psalms 78:51

78:51 He struck down all the firstborn in Egypt,

the firstfruits of their reproductive power ¹  in the tents of Ham.

Psalms 89:27

89:27 I will appoint him to be my firstborn son, ² 

the most exalted of the earth’s kings.

Psalms 105:36

105:36 He struck down all the firstborn in their land,

the firstfruits of their reproductive power. ³ 

[78:51]  ¹ tn Heb “the beginning of strength.” If retained, the plural form אוֹנִים (’onim, “strength”) probably indicates degree (“great strength”), but many ancient witnesses read “their strength,” which presupposes an emendation to אֹנָם (’onam; singular form of the noun with third masculine plural pronominal suffix).

[89:27]  ² sn The firstborn son typically had special status and received special privileges.

[105:36]  ³ tn Heb “the beginning of all their strength,” that is, reproductive power (see Ps 78:51).