Bukhari

Hadith Commentary:
The child was very young and nursing, therefore the Prophet (sallallahu alayhi wa sallam) considered it sufficient to merely sprinkle water over his urine.

It is also understood from this that when thick and putrid winds accumulate in the chest and cause discomfort, Indian costus (‘ud hindī) is beneficial in such cases.

The author of "Khawas al-Adwiyah" writes that marine costus (qisṭ baḥrī) is sweet, hot, and dry.

It strengthens the brain, the principal organs, sexual power, the liver, and the muscles.

It dissolves winds, is beneficial for neurological diseases such as paralysis, facial palsy, and tremors.

It kills intestinal worms, and induces urination and menstruation.

In the chapter, the intention is to mix both Indian and marine costus and make a snuff (nās), and to inhale it through the nose.

It is the root of a plant; in Hindi it is called "koot."

Hadith Commentary:
(1)
Due to intense heat, swelling occurs in the throats of children. Sometimes, blood accumulates and the throat becomes red, so women treat this by wrapping a cloth around their finger and pressing it firmly. At times, they apply ash to the finger and perform this action, which causes black blood to come out, and with its discharge, the child finds relief.
(2)
Nevertheless, this procedure causes pain to the child; therefore, the Messenger of Allah (sallallahu alayhi wa sallam) prescribed that Indian costus (qust al-hindi) should be ground and mixed with water or oil, and then instilled into the nose. In this way, the medicine naturally reaches the throat and the child finds comfort. The Messenger of Allah (sallallahu alayhi wa sallam) mentioned two out of seven diseases because, in that environment, these two illnesses were common: one was throat ailments in children, and the other was chest pain. Thus, for these two diseases, Indian costus (qust al-hindi) is very beneficial.
(Fath al-Bari: 10/184)