Parashas Vayakhel · Passuk 35:1
Torah Temimah points to classical source on this unit (verified).
English: The sages of Caesarea use “אֵלֶּה” as a mnemonic for the thirty-nine categories of labor on Shabbos: א׳, ל׳, and ה׳ total thirty-nine.
Derash by numerical-letter mnemonic: “אלה” signals the thirty-nine labors.
The word “אלה” is used as a mnemonic for the thirty-nine primary categories of Shabbos labor; this is a sign or hint, not the underlying derivation from the Mishkan.