Nasai

Hadith Commentary:
The meaning is that he (sallallahu alayhi wa sallam) would neither spend the entire night sleeping nor the entire night engaged in prayer; rather, the middle path was preferred by him (sallallahu alayhi wa sallam), and this is what is Sunnah.

Hadith Commentary:
In one narration, it is mentioned that when the time for suhoor (pre-dawn meal) would arrive, he would perform the witr prayer, and then, if there was a need, he would go to his wife.
(Fath al-Bari: 3/42)
From this narration, it is understood that if the Messenger of Allah (sallallahu alayhi wa sallam) felt the need for marital relations, he would fulfill this need after performing the tahajjud prayer, because this was most befitting for the Messenger of Allah (sallallahu alayhi wa sallam) in matters of worship. Thus, it is not established that the Messenger of Allah (sallallahu alayhi wa sallam) slept in a state of janabah (major ritual impurity) in the early part of the night; however, it is established that in the latter part of the night, he would lie down for a short while on his right side.
In any case, Imam Bukhari (rahimahullah) has proven from this hadith that the Messenger of Allah (sallallahu alayhi wa sallam) would wake up in the last part of the night and perform the tahajjud prayer.

Hadith Commentary:
Benefits and Issues:
From this hadith, it is understood that the Prophet (sallallahu alayhi wa sallam) would sometimes wake up early at night, and after completing the night prayer, he would have relations with his wife and then go back to sleep. Upon waking up quickly after the call to prayer (adhan) of Fajr, he would perform the ritual bath (ghusl) and then offer the Sunnah prayers of Fajr. The Sunnah prayers of Fajr were always performed before the obligatory Fajr prayer.

Commentary:
Benefit:
The Messenger of Allah (sallallahu alayhi wa sallam) practiced various methods regarding performing the night prayer (tahajjud) and resting at night.
One of these methods is also this.