Observing Prayer Early in the Period - Section 2 Mishkat al-Masabih 609, 610

Arabic hadith text
وَعَنْ أَبِي أَيُّوبَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ:" لَا تَزَالُ أُمَّتِي بِخَيْرٍ أَوْ قَالَ: عَلَى الْفِطْرَةِ مَا لَمْ يُؤَخِّرُوا الْمَغْرِبَ إِلَى أَنْ تَشْتَبِكَ النُّجُومُ ". رَوَاهُ أَبُو دَاوُد وَرَوَاهُ الدَّارمِيّ عَن الْعَبَّاس
Translation

Abu Ayyub reported God's Messenger as saying, “My people will continue to prosper (or he said, to follow Islam), as long as they do not postpone the sunset prayer till the stars are not in abundance.” Abu Dawud transmitted it and Darimi transmitted it from al-‘Abbas.