Sunan Abi Dawud Book 2, Hadith 398
The prophet (ﷺ) did not distinguish between the two surahs until the words “In the name of Allah, the Compassionate, the merciful” was revealed to him. These are the words of Ibn al-sarh.
The apostle of Allah (ﷺ) died, but he did not mention to us that surah al baraah ins a part of al-anfal.
Abu Dawood said: Al-sha’bl, Abu Malik, Qatadah, and Thabit b. ‘Umarah said: The prophet( may peace be upon him) did not write”In the name of Allah, the compassionate, the merciful” until Surah al-naml was revealed. This is the meaning of what they said. Further, this is a mursal traditional(omitting the name of the companion)
I stand up to pray and intend to prolong it; but when I hear the cry of a boy I shorten if for fear that his mother might be distressed.