The NJPS (in English) has this for Gen 1:7 -
God made the expanse, and it separated the water which was below the
expanse from the water which was above the expanse. And it was so.
First, וַיַּבְדֵּ֗ל consists of a conjunction and a verb (to separate), there is no pronoun. Further, the verb is בָּדל and in Gen 1:7 - it features prominently in the first three days as
- God divides the light from darkness (day 1)
- God divides waters above from waters below (day 2)
- God divides the sea from the land to create dry ground (day 3)
Thus, the verb appears in Gen 1:4, 6, 7, 14, 18. In the particular case of Gen 1:7, the verb is Hifil - Consecutive imperfect - third person masculine singular. Thus, if one wished to supply a pronoun, it would need to be "He" because the verb is masculine, based on the verb alone.
However, no such explicit pronoun is in the Hebrew text. The choice of pronoun depends on which noun is the antecedent.
- If we assume "God"/elohim is the antecedent, then "he" would be the appropriate pronoun; ie, God id the separating
- if we take the firmament/expanse to be the antecedent, the "it" is the appropriate pronoun.
Clearly, the latter has been assumed by the translators of the NJPS. By contrast, some versions avoid the problem and avoid the need for any inserted pronoun thus (BSB):
6 And God said, “Let there be an expanse between the waters, to separate the waters from the waters.” 7 So God made the expanse
and separated the waters beneath it from the waters above. And it was
so.
This is actually closer to the Hebrew which contains no pronouns.
APPENDIX - Gen 1:6
The text of Gen 1:6 provides another useful example to the above. A good literal translation of the verse is provided by NASB:
Then God said, “Let there be an expanse in the midst of the waters,
and let it separate the waters from the waters.”
Note that both the verb וִיהִ֣י ("and let") and מַבְדִּ֔יל ("divide/separate") are masculine singular. However, the subject of both these verbs is רָקִ֖יעַ ("firmament/expanse") which is also masculine. However, in English, impersonal nouns do not have gender and thus, the translators provide a neuter pronoun. An overly literal translation would end up being meaningless by saying:
Then God said, “Let there be an expanse in the midst of the waters,
and let him (ie, the firmament) separate the waters from the
waters.”
This is incorrect English.