Musnad Ahmad 978:1

'Ali ibn 'Asim narrated to us, from 'Ata' ibn al-Sa'ib, who said: I was sitting with 'Abdullah ibn Mughaffal al-Muzani, when two young men from the descendants of 'Umar entered and prayed two rak'ahs after the 'Asr prayer. He sent for them and called them, then said: "What is this prayer that you have prayed, when your father used to forbid it?" They said: "'A'ishah narrated to us that the Prophet, peace and blessings of Allah be upon him, prayed them at her place." He remained silent and did not reply to them with anything.