Sahih Muslim , Book 4, Hadith 1653 (USC-MSA) ⓘ
Jabir reported: The Messenger of Allah was asked about the prayer which was most excellent. He said: That in which the standing is longer. (This hadith is narrated by another chain of transmitters too.)
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، حَدَّثَنَا الأَعْمَشُ، عَنْ أَبِي سُفْيَانَ، عَنْ جَابِرٍ، قَالَ سُئِلَ رَسُولُ اللَّهِ صلى الله عليه وسلم أَىُّ الصَّلاَةِ أَفْضَلُ قَالَ " طُولُ الْقُنُوتِ " . قَالَ أَبُو بَكْرٍ حَدَّثَنَا أَبُو مُعَاوِيَةَ عَنِ الأَعْمَشِ .
also referenced under: Book 6, Hadith 198 (In-Book) & Hadith 756 (Reference)