TT #75 · Parshas Tazria · Aliyah 1 · Passuk 2
English: When a person has on the skin of the body a swelling, a rash, or a discoloration, and it develops into a scaly affection on the skin of the body, it shall be reported to Aaron the priest or to one of his sons, the priests.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:2
Torah Temimah cites Sanhedrin 34b for the argument whether skin-affliction examination requires three, like monetary litigation.
E-Daf — Sanhedrin 34b · Shas.org · Sefaria — source text and translation
English: One might argue that, just as monetary disputes require three judges, examination of a person’s body should require three priests.
Textual inference
The analogy to monetary cases raises a possible three-person requirement; the following unit gives the verse that resolves the question.