Narrated by Aisha (may Allah be pleased with her), she stated that the Messenger of Allah (ﷺ) sometimes shortened the prayer during travel and sometimes performed it in full.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 356
Hadith Takhrijإسناده ضعيف جداً: فإن إبراهيم بن محمد وطلحة بن عمرو متروكان. أخرجه البيهقي في معرفة السنن والآثار: 1514 - والدارقطني: 2/ 189 - وابن أبي شيبة: 8187.
It is narrated from Aisha (may Allah be pleased with her), she said: At first, the prayer was made obligatory as two rak'ahs, then the prayers performed in residence were increased, and the prayer during travel was kept as it was. Zuhri (may Allah have mercy on him) says: I asked, then why did Aisha (may Allah be pleased with her) herself perform the full prayer during travel? Urwah replied: She adopted the same interpretation as Uthman (may Allah be pleased with him).
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 357
Hadith Takhrijأخرجه البخاري: القصر، باب يقصر إذا خرج من موضعه: 1090، 350 - ومسلم: صلاة المسافرين، باب صلاة المسافرين قصرها: 685.
It is narrated from Ibn Umar (may Allah be pleased with them both) that when he prayed behind the Imam in Mina, he would perform four (obligatory) units, and when he prayed by himself, he would perform two units.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 358
Hadith Takhrijأخرجه البيهقي في معرفة السنن والآثار: 1596 - ومالك في الموطأ: الصلاة، باب صلاة المسافر إذا كان إمامًا وراء الإمام.
It is narrated from Ibn Umar (may Allah be pleased with them both) that during travel he would not perform anything before or after the obligatory prayer, except for the Tahajjud prayer.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 359
Hadith Takhrijأخرجه البيهقي في معرفة السنن والآثار: 1625 - ومالك في الموطأ: الصلاة، باب صلاة النافلة في السفر بالنهار والليل والصلاة على الدابة.