"I asked Lahiq about the two Rak'ahs before sunset. He said: "Abdullah bin Az-Zubair used to pray them, and Mu'awiyah sent word to him asking: 'What are these two Rak'ahs at sunset?' He had to refer to Umm Salamah, and Umm Salamah said: 'The Messenger of Allah ﷺ used to pray two Rak'ahs before 'Asr, then he was distracted and did not pray them, so he prayed them when the sun set, and I never saw him pray them before or after that.'" (Using translation from Nasāʾī 581)  

أُمُّ سَلَمَةَ «إِنَّ رَسُولَ اللهِ ﷺ كَانَ يُصَلِّي الرَّكْعَتَيْنِ قَبْلَ الْعَصْرِ فَشُغِلَ عَنْهُمَا فَرَكَعَهُمَا حِينَ غَابَتِ الشَّمْسُ وَلَمْ أَرَهُ يُصَلِّيهِمَا قَبْلُ وَلَا بَعْدُ»