Rabbi Yitzchak said: The “adornments of the scribes” are a law given to Moshe at Sinai; and “afterward she shall go” is [one of] the adornments of the scribes.
On the daf / in context: Certain words that appear only for stylistic completeness are nevertheless part of the received text and may not be altered or omitted.
Type of Learning
Custom (Bavli — ittur soferim as halachah le-Moshe mi-Sinai)
What Is Learned
Words that serve only stylistic elegance (ittur soferim) are still integral to the Torah text transmitted from Sinai and may not be changed.