Hadith 580

It was narrated that Umm Salamah said: "The Messenger of Allah (PBUH) got distracted and did not pray the two Rak'ahs before 'Asr so he prayed them after 'Asr."

أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا وَكِيعٌ، قَالَ حَدَّثَنَا طَلْحَةُ بْنُ يَحْيَى، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنْ أُمِّ سَلَمَةَ، قَالَتْ شُغِلَ رَسُولُ اللَّهِ صلى الله عليه وسلم عَنِ الرَّكْعَتَيْنِ قَبْلَ الْعَصْرِ فَصَلاَّهُمَا بَعْدَ الْعَصْرِ ‏.‏

Reference: 1105840
In-book reference: Book 6, Hadith 580
Hadith 580 - The Book of the Times (of Prayer) - Sunan an-Nasa'i - Sunnah.com