In Hebrew, we often find the verb הָיָה (hāyâ) followed by the preposition ל prefixed to a noun used to indicate that something was made into something (i.q. Latin est factum quiddam in quiddam).
On the verb הָיָה, Heinrich Friedrich Wilhelm Gesenius wrote,1
For example, in Gen. 2:7, it is written: וַיְהִי הָאָדָם לְנֶפֶשׁ חַיָּה (wayhî hāʾādām lĕnepeš ḥayyâ)—“and Adam became a living soul.” Since the preposition ל is commonly translated as “into,”2 we English readers may wish to translate the phrase into English as “and Adam became into a living soul,” but of course, we need to accept that it is a Hebrew idiom that does not require such a literal translation into English. The idea is simply that Adam became a living soul. As you might expect, Jerome translated the Hebrew into Latin as et factus est homo in animam viventem.
Yet, Jerome did not always maintain the same rigid syntax elsewhere. For example, in his translation of Num. 26:10, he translated the Hebrew וַיִּהְיוּ לְנֵס (wayyihyû lĕnēs) into Latin as et factum est grande miraculum, thus omitting the preposition in.
Of course, rather than interpreting the Latin as “something became something” (essentially middle voice), it would be acceptable to interpret it as “something was made into something” (passive voice), and that may be what Jerome had in mind when he translated those phrases into Latin with the inclusion of the preposition in.
Gesenius, Heinrich Friedrich Wilhelm. Gesenius’s Hebrew and Chaldee Lexicon to the Old Testament Scriptures. Trans. Tregelles, Samuel Prideaux. London: Bagster, 1860.
1 p. 221
2 p. 422, ל, (A) (3)