سُنَنُ النَّسَائِيِّ
Sunan an-Nasa’i 601
The Book of the Times (of Prayer)
Combining Two Prayers While A Resident
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 .
It was narrated that Ibn 'Abbas said: "The Messenger of Allah (ﷺ) prayed Zuhr and 'Asr together, and Maghrib and 'Isha' together, when there was no fear and he was not traveling."
Sunan an-Nasa'i, 601Sahih (Darussalam)