Sunan an-Nasa'i, Book 6, Hadith 608 (In-Book) ⓘ
It was narrated that Ibn 'Abbas said: "The Messenger of Allah prayed Zuhr and 'Asr together, and Maghrib and 'Isha' together, when there was no fear and he was not traveling."
أَخْبَرَنَا قُتَيْبَةُ، عَنْ مَالِكٍ، عَنْ أَبِي الزُّبَيْرِ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ صَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم الظُّهْرَ وَالْعَصْرَ جَمِيعًا وَالْمَغْرِبَ وَالْعِشَاءَ جَمِيعًا مِنْ غَيْرِ خَوْفٍ وَلاَ سَفَرٍ .
also referenced under: Volume 1, Book 6, Hadith 602 (DarusSalam)