عَنْ عَائِشَةَ رَضِيَ اللّهُ عَنْهَا قَالَتْ: كَانَ رَسُولُ اللّهِ صَلَّى اللّهُ عَلَيْهِ وَسَلَّمَ يُدْرِكُهُ الْفَجْرُ وَهُوَ جُنُبٌ مِنْ أَهْلِهِ، ثُمَّ يَغْتَسِلُ وَيَصُومُ. مُتَّفَقٌ عَلَيْهِ.
Aisha (may Allah be pleased with her) reported: The dawn would come upon the Messenger of Allah (peace and blessings be upon him) while he was in a state of major ritual impurity (junub) from [relations with] his family; then he would bathe and fast. Agreed upon (al-Bukhari and Muslim).
الشرح · explanation
يدركه الفجر: أي يدخل وقت الفجر ويلزمه الصوم وهو جنب، ولا يعني هذا أبدا أنها تدركه الصلاة فيتأخر عنها
"The dawn would come upon him": that is, the time of dawn would enter and fasting would become obligatory upon him while he was in a state of major ritual impurity; this does not at all mean that the [dawn] prayer would come upon him such that he delayed it.
الدروس · lessons
أنّ من أصبح وهو جنب فإن ذلك لا يمنعه من الصوم ولا يبطله. لا علاقة للصيام بالجنابة لأنّ الطهارة ليست من شروط الصيام.
Whoever reaches morning in a state of major ritual impurity — this does not prevent him from fasting nor invalidate his fast. There is no connection between fasting and major ritual impurity, because ritual purity is not a condition for the validity of fasting.