TT #162 · Parshas Shemini · Aliyah 6 · Passuk 29
Chabad.org — Vayikra Chapter 11 with Rashi
English: These are the creatures that are impure among the swarming things that swarm on the earth: the weasel, the mouse, and the various kinds of lizard.
Meilah 17a.
E-Daf.com — Meilah 17a (Tsurras Hadaf)
וְזֶה לָכֶם הַטָּמֵא. שָׁאַל רַבִּי מַתְיָא בֶּן חֲרָשׁ אֶת רַבִּי שִׁמְעוֹן בֶּן יוֹחַאי, מִנַּיִן לְדַם שְׁרָצִים שֶׁהוּא טָמֵא? אָמַר לֵיהּ, דְּאָמַר קְרָא וְזֶה לָכֶם הַטָּמֵא.
Proof from wording — The verse itself is cited as the source for the impurity of the blood of swarming creatures.
The verse supplies the basis for the impurity of sheretz blood.