What is the main topic of Bulugh al-Maram Hadith 112?

Bulugh al-Maram Hadith 112 is from chapter "The Book of Purification". Summary: "If you perform ablution rinse your mouth" .

Bulugh al-Maram: Hadith 112

1. The Book of Purification

1/8 Chapter:

باب الغسل وحكم الجنب

112

Bulugh al-Maram

وَلِأَبِي دَاوُدَ فِي رِوَايَةٍ: { إِذَا تَوَضَّأْتَ فَمَضْمِضْ } (51)‏ .‏

In another verson of Abu Da'ud is:

"If you perform ablution rinse your mouth" .

Reference: Bulugh al-Maram 39
In-book : Book 1, Hadith 46
English translation : Book 1, Hadith 45