Sahih Muslim Book - 6, Hadith - 1766

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِى شَيْبَةَ حَدَّثَنَا حَفْصٌ وَأَبُو مُعَاوِيَةَ عَنِ الأَعْمَشِ عَنْ أَبِى سُفْيَانَ عَنْ جَابِرٍ قَالَ قَالَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- « مَنْ خَافَ أَنْ لاَ يَقُومَ مِنْ آخِرِ اللَّيْلِ فَلْيُوتِرْ أَوَّلَهُ وَمَنْ طَمِعَ أَنْ يَقُومَ آخِرَهُ فَلْيُوتِرْ آخِرَ اللَّيْلِ فَإِنَّ صَلاَةَ آخِرِ اللَّيْلِ مَشْهُودَةٌ وَذَلِكَ أَفْضَلُ ». وَقَالَ أَبُو مُعَاوِيَةَ مَحْضُورَةٌ.

It was narrated that Jabir said: "The Messenger of Allah (s.a.w) said: 'Whoever fears that he will not get up at the end of the night, let him pray Witr at the beginning. Whoever is sure that he will get up at the end of the night, let him pray Witr at the end, for prayer at the end of the night is witnessed, and that is better." Abu Mu'awiyah (in his narration) said: "is attended."