Parashas Metzora · Passuk 15:05
Chabad.org — English translation + Rashi
Torah Temima points to Toras Kohanim.
English: “His bed” — his bed, and not a rope extending from the bed less than five [tefachim] or more than ten; his bed, and not threads extending from the knot beyond three fingerbreadths.
Limits of bed appendages
Chazal define which extensions of a bed are still considered part of the midras body itself for impurity purposes.