Nasai

1:
This contains evidence that a person in a state of major ritual impurity (janabah) may sleep without performing ablution (wudu) or taking a ritual bath (ghusl).
The action of the Messenger of Allah (sallallahu alayhi wa sallam) here is to clarify permissibility, so that the ummah does not fall into hardship.
As for the next hadith, in which you (sallallahu alayhi wa sallam) would perform ablution (wudu) before sleeping after janabah, then that is superior.
There is no contradiction between the two hadiths.

Benefits and Issues:
➊ Reflect on the questions of the righteous of the Ummah, for their foundation was the seeking of Allah’s pleasure, the longing for His closeness, and the emulation of the life of the Messenger of Allah (sallallahu alayhi wa sallam).
➋ It is permissible to delay the ritual bath (ghusl) of major impurity (janabah), but the emphasized recommended practice is to perform ablution (wudu) before sleeping.
➌ It is permissible to perform the Witr prayer at any time during the night, but the encouragement and preference is to perform it in the last part of the night (after the Tahajjud prayer).
➍ The true time and occasion for the recitation of the Qur’an by the Messenger of Allah (sallallahu alayhi wa sallam), and likewise the noble Companions (radi Allahu anhum), used to be during the night in the Tahajjud prayer.
➎ In this recitation, it is very important to be considerate of the household, so that raising the voice too much does not cause disturbance to others.

Benefits and Issues:
➊ Imam Abu Dawood rahimahullah has reported that there is some doubt regarding this hadith, and Imam Tirmidhi rahimahullah has also indicated the same. However, he also stated that this narration from Abu Ishaq has been transmitted by Shu’bah, Thawri, and several others. Among our contemporary scholars and hadith experts, Allamah Ahmad Muhammad Shakir and Shaykh al-Albani have declared this hadith to be authentic. See: [سنن ترمذي شرح احمد محمد شاكر، 1؍202۔ 206]
And in "Adab az-Zafaf" by Shaykh al-Albani, and as a summary, this excerpt is presented from Allamah Ibn Qutaybah’s "Ta’wil Mukhtalif al-Hadith": [306]
“In the aforementioned matter, all these actions are permissible: whoever wishes may perform ablution (wudu) after intercourse and then sleep, whoever wishes may wash only his private parts and his hands, and whoever wishes may sleep as he is. However, performing ablution is superior, and the Messenger of Allah sallallahu alayhi wa sallam sometimes acted upon the first option to establish its virtue, and sometimes upon the second, so that concession (rukhsah) remains and people find ease in practice. Therefore, whoever wishes to act upon what is superior may do so, and whoever wishes to suffice with the concession may do so.” «والله اعلم بالصواب»

405. Commentary: Benefit: For clarification, see Hadith 223 and its benefit.

223. Commentary:
➊ The purpose of the chapter is to clarify whether, if a person becomes in a state of major ritual impurity (junub) due to intercourse or a wet dream at the beginning of the night, it is obligatory for him to perform the ritual bath (ghusl) immediately, or if he can delay it until the morning prayer. From the answer of Aisha (radi Allahu anha), it is understood that there is allowance to delay it until the morning, although it is preferable to perform the ritual bath early. «والله أعلم»
➋ A Muslim should adopt the beautiful example (uswah hasanah) of the Prophet Muhammad (sallallahu alayhi wa sallam) in his daily routines, and if he is unaware of something, he should inquire about it from the people of knowledge.

Commentary:
(1)
The meaning of sleeping without touching water is that neither a ritual bath (ghusl) nor ablution (wudu) was performed, and thus one slept in this state.

(2)
Our esteemed researcher has declared this hadith weak in its chain of narration (sanadan), but in light of other narrations, it is better and more virtuous to sleep after performing ablution (wudu), as will be mentioned in the next chapter.

English Translation:
Isma'il's intent is that this narration is transmitted only through the chain “Abu Ishaq from Aswad from Aisha radi Allahu anha,” therefore, there should be another chain as well to support Abu Ishaq. However, through other routes, this narration is deemed sahih (authentic) or hasan (good). (For further details, see Ahmad Shakir al-Misri rahimahullah’s commentary on Tirmidhi: 1/202)