Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1819
Aswad and Masruq reported: We bear testimony to the fact that 'A'isha said: Never was there a day that he (the Holy Prophet) was with me and he did not observe two rak'ahs of prayer in my house, i. e. two rak'ahs after the Asr.