Ikrama عكرمة · The Book on Traveling

"The Messenger of Allah traveled on a journey and he prayed two Rak'ah for nineteen days." Ibn Abbas said: "So when we would stay somewhere for nineteen (days) we would pray two Rak'ah , and if we stayed longer than that we would complete the Salat."

"The Messenger of Allah prostrated for it - meaning (in Surat) An-Najm - and so did the Muslims, the idolaters, the Jinns, and the people."

"I saw the Messenger of Allah prostrating for (Surat) Sad." Ibn Abbas said: "It is not one of the resolute prostrations."

"The Messenger of Allah would glance toward the right and the left during Salat but he would not turn his neck to look behind him."