It was narrated from Abu Salamah that he asked 'Aishah about the two prostrations (Rak'ahs) that the Messenger of Allah (ﷺ) used to pray after 'Asr. She said:
"He used to pray them before 'Asr, but if he got distracted or forgot them, he would pray them after 'Asr, and if he did a prayer he would be constant in it."