Sunan Abi Dawud, Hadith 1209 ⓘ
This tradition has also been transmitted by Ibrahim b. Musa al-Razi, from 'Isa, on the authority of Ibn Jabir to the same effect. Abu Dawud said: 'Abd Allah b. al-'Ala' narrated on the authority of Nafi' saying: When the twilight was about to disappear, he alighted and combined both (the prayers).
حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى الرَّازِيُّ، أَخْبَرَنَا عِيسَى، عَنِ ابْنِ جَابِرٍ، بِهَذَا الْمَعْنَى . قَالَ أَبُو دَاوُدَ وَرَوَاهُ عَبْدُ اللَّهِ بْنُ الْعَلاَءِ عَنْ نَافِعٍ، قَالَ حَتَّى إِذَا كَانَ عِنْدَ ذَهَابِ الشَّفَقِ نَزَلَ فَجَمَعَ بَيْنَهُمَا .
also referenced under: Hadith 1213 (DarusSalam) & Book 4, Hadith 1209 (USC-MSA)