What is the main topic of Bulugh al-Maram Hadith 147?

Bulugh al-Maram Hadith 147 is from chapter "The Book of Purification". Summary: and Muslim admitted that he dropped this addition deliberately.

Bulugh al-Maram: Hadith 147

1. The Book of Purification

1/9 Chapter:

باب التيمم

147

Bulugh al-Maram

وَأَشَارَ مُسْلِمٌ إِلَى أَنَّهُ حَذَفَهَا عَمْدً ا (87)‏ .‏

and Muslim admitted that he dropped this addition deliberately.

Reference: Bulugh al-Maram 68
In-book : Book 1, Hadith 81
English translation : Book 1, Hadith 74