Translation
(4) Prayer (Kitab Al-Salat): Detailed Rules of Law about the Prayer during Journey
كتاب صلاة السفر
(425) Chapter: Combining Between Two Prayers
(5) باب الْجَمْعِ بَيْنَ الصَّلاَتَيْنِ
Sunan Abi Dawud 1213 

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 ‏.‏
Grade :  Sahih (Al-Albani) صحيح  (الألباني)حكم :
Reference : Sunan Abi Dawud 1213
In-book reference : Book 4, Hadith 16
English translation : Book 4, Hadith 1209