Muwatta Malik, Book 9, Hadith 4 (USC-MSA) ⓘ

Yahya related to me from Malik from Abu'z Zubayr al-Makki from Said ibn Jubayr that Abdullah ibn Abbas said, "The Messenger of Allah, may Allah bless him and grant him peace, prayed dhuhr and asr together and maghrib and isha together, and not out of fear nor because of travelling."

حَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزُّبَيْرِ الْمَكِّيِّ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّهُ قَالَ صَلَّى رَسُولُ اللَّهِ صلى الله عليه وسلم الظُّهْرَ وَالْعَصْرَ جَمِيعًا وَالْمَغْرِبَ وَالْعِشَاءَ جَمِيعًا فِي غَيْرِ خَوْفٍ وَلاَ سَفَرٍ ‏.‏

(with regards to above) Malik said, "I believe that was during rain."