(1) باب صَلاَةِ الْمُسَافِرِينَ وَقَصْرِهَا
Ibn 'Abbas reported:
Allah has prescribed the prayer by the tongue of your Apostle (ﷺ) as two rak'ahs for the traveller, four for the resident, and one in danger. (JA)
Reference (JA): Sahih Muslim 687 b (JA)
In-book reference (JA): Book 6, Hadith 7 (JA)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1464 (JA)