NASAI-KUBRA 384:
from Raʾayt ʿAbdullāh b. ʿUmar Ṣallá Bijamʿ Faʾaqām Faṣallá al-Maghrib Thalāth Thum Ṣallá al-ʿIshāʾ Rakʿatayn Thum —
"Ibn 'Umar did not offer more than two rak'ahs when traveling, and he did not offer any prayer before or after that. It was said to him: 'What is this?' He said: 'This is what I saw the Messenger of Allah ﷺ doing.'" (Using translation from Nasāʾī 1457)
الكبرى للنسائي ٣٨٤:
عن رءيت عبد الله بن عمر صلى بجمع فءقام فصلى المغرب ثلاث ثم صلى العشاء ركعتين ثم —
هَكَذَا رَأَيْتُ رَسُولَ اللهِ ﷺ صَنَعَ