Deuteronomy 21:17

21:17 Rather, he must acknowledge the son of the less loved ¹  wife as firstborn and give him the double portion ²  of all he has, for that son is the beginning of his father’s procreative power ³  – to him should go the right of the firstborn.

Psalms 78:51

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

the firstfruits of their reproductive power ⁴  in the tents of Ham.

Psalms 105:36

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

the firstfruits of their reproductive power. ⁵ 

[21:17]  ¹ tn See note on the word “other” in v. 15.

[21:17]  ² tn Heb “measure of two.” The Hebrew expression פִּי שְׁנַיִם (piy shÿnayim) suggests a two-thirds split; that is, the elder gets two parts and the younger one part. Cf. 2 Kgs 2:9; Zech 13:8. The practice is implicit in Isaac’s blessing of Jacob (Gen 25:31-34) and Jacob’s blessing of Ephraim (Gen 48:8-22).

[21:17]  ³ tn Heb “his generative power” (אוֹן, ’on; cf. HALOT 22 s.v.). Cf. NAB “the first fruits of his manhood”; NRSV “the first issue of his virility.”

[78:51]  ⁴ 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).

[105:36]  ⁵ tn Heb “the beginning of all their strength,” that is, reproductive power (see Ps 78:51).