Praise be to Allah,
It is recommended for the spouses to take a bath(ghusl) after sexual relations. However, it is not obligatory for them to take a Ghusl before sleeping. This means that if they want to sleep without taking Ghusl, they will not be sinful.
A’isha (may Allah be pleased with her) relates: “The Messenger of Allah (Allah bless him & give him peace) would sleep in a state of major ritual impurity (janaba) without touching water.” [i]
Thus, it proves that it is better to hasten towards performing Ghusl but it is not obligatory.
As for the hadith:
lbn ‘Abbas reported that Allah’s Messenger said: There are three individuals whom the angels do not approach a junub, a drunk person, and a man who wears khaliiq”[ii]
Ibn ul-Athir (~) said:
“Khaluq is prohibited because it is a women’s perfume… and a junub here probably means one whose habit is not to perform ghusl from janabah, so that most of the time he would be junub, which is an indication of weak faith and evil heart”[iii].
Timing of taking Ghusl after sexual intercourse.
Ghudayf ibn al-Harith relates that “I asked A’isha, “Have you seen the Messenger of Allah (Allah bless him & give him peace) having a ritual bath at the beginning of the night or at the end?” She replied, “Sometimes he would have a bath at the beginning of the night and sometimes at the end.” And so I said, “Allah is Most Great. All Praise be to Allah Who put ease in the matter…”[iv]
Thus, It is allowed to perform Ghusl immediately after intercourse or delay it till Fajr.
Perform a ritual ablution (wudu) instead.
A’isha (may Allah be pleased with her) relates: “Whenever the Messenger of Allah (Allah bless him & give him peace) intended to sleep in a state of major ritual impurity, he would wash his private parts and perform ablution like that for the prayer.” [v]
Umar ibn al-Khattab (may Allah be pleased with him) relates that the Messenger of Allah (Allah bless him & give him peace) said to him: “Perform ablution and wash your private parts, then go to sleep[vi].”
In another narration,
A’ishah also reported: “When Allah’s Messenger (Allah bless him & give him peace) was junub and wanted to go to sleep, he would first perform wudu or tayammum.”[vii]–
One should at least wash his private parts as it is more hygienic, closer to the fitra, and is better for the body.
Wudu is not obligatory
Few scholars among the Malikis thought that Wudu is obligatory on one who wants to sleep after sexual intercourse.
The Zaahiriyyah and Ibn Habeeb among the Maalikis thought that it was obligatory[viii] for the person who is in a state of impurity to do wudoo’, on the basis of the hadeeth of ‘Umar:
Ibn ‘Umar (may Allaah be pleased with him) who said that ‘Umar said, “O Messenger of Allaah, may anyone of us sleep when he is in a state of impurity?” He said, “yes, if he does wudoo’.” (Agreed upon).
However, performing Wudu is not obligatory and is Mustahab. We have mentioned earlier that prophet (Allah bless him & give him peace) would sleep after sexual intercourse without touching water.
On the authority of Ibn ‘Umar who said: “O Messenger of Allah, should we go to sleep in a state of janaba?” The Prophet answered: “Yes, after making wudhuu[ix].”
In another version: “Perform wudhuu’ and wash your private parts, and then sleep.[x]”
And, in another version: “Yes, you can perform wudhuu’, sleep, and bathe whenever you want[xi].” And, in still another version: “Yes, and perform wudhuu’ if you wish.[xii]”
This last version proves that this wudhuu’ is not obligatory[xiii].
In another version narrated by ‘Aa’ishah , she said: “”He used to spend the night in a
state of janaba until Bilal came in the morning to make the adhaan. Then, he would
get up, bathe while I looked at the water dripping from his head, and go out. Then, I would hear his voice in the Fajr prayer. Then, he would remain fasting.” Mutarrif said: “I said to Aamir: In the month of Ramadhaan?” He said: “Yes, in Ramadhaan and in other than Ramadhaan[xiv].”
Sheikh Albani( May Allah have mercy on him) says,
This wudhuu’ is not obligatory, but is very highly and definitely commendable. This (i.e.its not being obligatory) is based on the hadith narrated by ‘Umar in which he asked the Prophet: “Should we go to sleep in a state of janaba?” To which the Prophet answered: “Yes, and perform wudhuu’ if you wish.” [Ibn Hibbaan: Saheeh]. This is also supported by other hadith, among them a hadith narrated by ‘Aa’ishah who said: “The Prophet used to sleep in a state of janaba without having touched water, until he would get up later and bathe.”[xv]
Conclusion
It is best to perform ghusl after sexual intercourse with spouse and if that is not possible then Wudu is highly recommended. As stated above, if one sleeps without wudu in janabah, then he will not be sinful. Allah Knows Best.
[i] (Sunan al-Tirmidhi 118, Sunan Abi Dawud 230 and Sunan Ibn Majah 581)
[ii] Khaluq: A yellowish/reddish mixed perfume made from Saffron and other ·
perfumes
[iii] the muslim family- 2- closer than garment, MUHAMMAD MUSTAFA AL-JIBALI, PDF, PP-35
[iv] (Sunan Abi Dawud 228 and others)
[v] (Sahih al-Bukhari 284 and Sahih Muslim 305)
[vi] Sahih al-Bukhari 286 and Sahih Muslim 306
[vii] Recorded by al-BayhaqI. Verified to be authentic by al-AlbanI (Adiib uz-Zifiif pp. 117-118).
[viii] https://islamqa.info/en/answers/3963/is-it-necessary-for-husband-and-wife-to-perform-ghusl-straight-after-intercourse
[ix] [Al-Bukhaaree and Muslim].
[x] [Al -Bukhaaree and Muslim].
[xi] [Muslim and al-Baihaqi].
[xii] [Ibn Khuzima and Ibn Hibban: Saheeh
[xiii] THE ETIIQUETTES OF MARRIIAGE AND WEDDIING, Sheikh Muhammed Nasirudeen al-Albanee, pdf-pp14
[xiv] [Ibn Abi Shaiba, Ahmad and others: Saheeh].
[xv] THE ETIIQUETTES OF MARRIIAGE AND WEDDIING Sheikh Muhammed Nasirudeen al-Albanee, pdf,pp15