The Mother of the Believers, Lady Umm Salamah, and the Mother of the Believers, Lady Aisha (may Allah be pleased with them both), reported that the Noble Prophet (peace and blessings be upon him) would sometimes enter the morning in a state of major ritual impurity due to intercourse, and yet he would still fast.
Hadith Takhrijاس روایت کی سند صحیح اور حدیث متفق علیہ ہے۔ دیکھئے: [بخاري 1926] ، [مسلم 1109] ، [أبويعلی 4427] ، [ابن حبان 3487]
Brief Explanation
(Commentary on Hadith 1762)
By the action of the Prophet of Islam, Muhammad Mustafa sallallahu alayhi wa sallam, ease was established for the Ummah: if a person engages in marital relations before the true dawn (subh sadiq) and is unable to perform the ritual bath (ghusl), then he may perform the ritual bath even after the call to prayer (adhan), and his fast will be valid.
Some of the Companions had hesitation regarding this matter, but when the Mothers of the Believers (Ummahat al-Mu'minin) informed them that the Master of Creation sallallahu alayhi wa sallam performed the ritual bath of major impurity (ghusl janabah) after dawn had occurred and also kept the fast, their hesitation was removed, and they retracted their previous statements. There was consensus established that if a person in a state of major impurity (junub) bathes after dawn has occurred, then his fast—whether obligatory or voluntary—will be valid, and there is no need to make it up (qada).
However, delaying the ritual bath (ghusl) after the true dawn (subh sadiq) is not appropriate, because it will result in delaying the Fajr prayer.