Parashas Vaeira · Passuk 8:15
Chabad.org — English translation + Rashi
Torah Temimah points to Sanhedrin 67b (verified).
Sefaria — Exodus 8:15
Sefaria — Sanhedrin 67b
E-Daf — Sanhedrin 67b
English: “This is the finger of God.” Rabbi Elazar says this teaches that a demon cannot create a creature smaller than a barley grain; Rav Pappa says that even a camel cannot be created by a demon, but larger creatures can be gathered whereas smaller ones cannot.
On the daf / in context: See the cited source for the full section.
Talmudic analysis of the limits of demonic creation
Chazal explain why Pharaoh’s magicians could not reproduce the plague of lice: their supernatural agents could not create or gather creatures of sufficiently small size.