Chapter - Section 1 Mishkat al-Masabih 681

Arabic hadith text
وَعَن سَمُرَةَ بْنِ جُنْدُبٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَا يَمْنَعَنَّكُمْ مِنْ سُحُورِكُمْ أَذَانُ بِلَالٍ وَلَا الْفَجْرُ الْمُسْتَطِيلُ وَلَكِنِ الْفَجْرُ الْمُسْتَطِيرُ فِي الْأُفق» رَوَاهُ مُسلم وَلَفظه لِلتِّرْمِذِي
Translation

Samura b. Jundub reported God’s Messenger as saying, “Do not let Bilal’s adhan or the false dawn prevent you from taking your morning meal [in Ramadan], but only the dawn which is widely spread in the horizon.” Muslim transmitted it, but the wording is Tirmidhi’s.