Bukhari

Hadith Commentary:
From this hadith, both issues are established: the permissibility of taking a ritual bath (ghusl) for the fasting person, and performing the ritual bath of major impurity (ghusl janabah) after the onset of Fajr while in a state of fasting. Since every possible ease has been taken into consideration in the Shari‘ah, the Messenger of Allah (sallallahu alayhi wa sallam), through his exemplary practice, has practically demonstrated these concessions.

Hadith Commentary:
(1)
Two rulings are established from these hadiths:
➊ Performing the ritual bath (ghusl) for major ritual impurity (janabah) after the break of dawn (fajr) but before the prayer, while in a state of fasting.
➋ The permissibility of performing the ritual bath (ghusl) for a fasting person.
In the pure Shariah, every possible ease for the servants has been taken into consideration.
The Messenger of Allah (sallallahu alayhi wa sallam), through his blessed example, practically demonstrated these concessions.
(2)
The purpose of these hadiths is that the Messenger of Allah (sallallahu alayhi wa sallam) would have relations with his wives, and if he fell asleep and morning came while he was still in a state of major ritual impurity (janabah), he would begin the fast in that state, then perform the ritual bath (ghusl) and offer the prayer.
From this, it is understood that major ritual impurity (janabah) does not invalidate the fast.