The dawn broke upon the Messenger of Allah ﷺ during the Ramadan in a state of junub not because of sexual dream (but on account of intercourse) and he washed himself and observed fast.
أَنَّ عَائِشَةَ زَوْجَ النَّبِيِّ ﷺ قَالَتْ قَدْ كَانَ رَسُولُ اللَّهِ ﷺ يُدْرِكُهُ الْفَجْرُ فِي رَمَضَانَ وَهُوَ جُنُبٌ مِنْ غَيْرِ حُلُمٍ فَيَغْتَسِلُ وَيَصُومُ
(At times) in Ramadan the Prophet ﷺ used to take a bath in the morning not because of a wet dream and would continue his fast.
عَائِشَةُ ؓ كَانَ النَّبِيُّ ﷺ يُدْرِكُهُ الْفَجْرُ {جُنُبًا} فِي رَمَضَانَ مِنْ غَيْرِ حُلُمٍ فَيَغْتَسِلُ وَيَصُومُ
[Machine] Aisha and Umm Salamah, both wives of the Prophet ﷺ , said, "The Messenger of Allah ﷺ would wake up in a state of janabah (ritual impurity) without having had any sexual dream during Ramadan, and then he would observe fasting."
أَنَّ عَائِشَةَ وَأُمَّ سَلَمَةَ زَوْجَيِ النَّبِيِّ ﷺ قَالَتَا «كَانَ رَسُولُ اللَّهِ ﷺ يُصْبِحُ جُنُبًا مِنْ غَيْرِ احْتِلَامٍ فِي رَمَضَانَ ثُمَّ يَصُومُ»
(At times) in Ramadan the Prophet ﷺ used to take a bath in the morning not because of a wet dream and would continue his fast. (Using translation from Bukhārī 1930)
كَانَ رَسُولُ اللهِ ﷺ «يُدْرِكُهُ الْفَجْرُ فِي رَمَضَانَ وَهُوَ جُنُبٌ مِنْ غَيْرِ حُلْمٍ فَيَغْتَسِلُ ثُمَّ يَصُومُ»