Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
ahmad:8145 –

[Machine] "And the Messenger of Allah ﷺ said: 'When the call to prayer for Fajr prayer is announced and one of you is in a state of sexual impurity (janabah), let him not fast on that day.'"  

أحمد:٨١٤٥ –

وَقَالَ رَسُولُ اللهِ ﷺ إِذَا نُودِيَ لِلصَّلَاةِ صَلَاةِ الصُّبْحِ وَأَحَدُكُمْ جُنُبٌ فَلَا يَصُمْ يَوْمَئِذٍ  

See similar narrations below:

Collected by Ibn Ḥibbān
ibnhibban:3485 – ʿAbdullāh b. Muḥammad al-Azdī > Isḥāq b. Ibrāhīm > ʿAbd al-Razzāq > Maʿmar > Hammām b. Munabbih > Abū Hurayrah

[Machine] The Messenger of Allah ﷺ said: "If the call for Fajr prayer is made and one of you is in a state of junub (sexual impurity), then he should not fast that day."  

ابن حبّان:٣٤٨٥ – أَخْبَرَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ الْأَزْدِيُّ قَالَ حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ قَالَ أَخْبَرَنَا عَبْدُ الرَّزَّاقِ قَالَ أَخْبَرَنَا مَعْمَرٌ عَنْ هَمَّامِ بْنِ مُنَبِّهٍ عَنْ أَبِي هُرَيْرَةَ قَالَ

قَالَ رَسُولُ اللَّهِ ﷺ «إِذَا نُودِيَ بِالصَّلَاةِ صَلَاةِ الصُّبْحِ وَأَحَدُكُمْ جُنُبٌ فَلَا يَصُومُ يَوْمَئِذٍ»