What is the main topic of Bulugh al-Maram Hadith 159?

Bulugh al-Maram Hadith 159 is from chapter "The Book of Purification". Summary: And Ahmad said that there is no authentic Hadith in this chapter.

Bulugh al-Maram: Hadith 159

1. The Book of Purification

1/10 Chapter:

باب الحيض

159

Bulugh al-Maram

وَقَالَ أَحْمَدُ: لَا يَصِحُّ فِي هَذَا اَلْبَابِ شَيْءٌ.‏

And Ahmad said that there is no authentic Hadith in this chapter.

Reference: Bulugh al-Maram 76
In-book : Book 1, Hadith 93
English translation : Book 1, Hadith 82