مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3325
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Sa’eed bin Shufayy that he heard Ibn ‘Abbas (رضي الله عنه) say: The Messenger of Allah (ﷺ) used to pray two rak'ahs (shortening the four-rak'ah prayers) when travelling,
Musnad Ahmad 3349Its isnad is saheeh]