What is the main topic of Bulugh al-Maram Hadith 126?

Bulugh al-Maram Hadith 126 is from chapter "The Book of Purification". Summary: and Ahmad said that nothing is authenticated in it.

Bulugh al-Maram: Hadith 126

1. The Book of Purification

1/8 Chapter:

باب الغسل وحكم الجنب

126

Bulugh al-Maram

قَالَ أَحْمَدُ: لَا يَثْبُتُ فِيهِ شَيْء ٌ (66)‏ .‏

and Ahmad said that nothing is authenticated in it.

Reference: Bulugh al-Maram 51
In-book : Book 1, Hadith 60
English translation : Book 1, Hadith 56