Abu Dawud Book 2, Hadith Number 1274.

Chapter : The view that the praying of the two rakahs after the afternoon prayer is permissible when the sun is at its height.

Narated By Al-Aswad and Masruq : We bear witness that ‘Aisha said: Not a day passed but the Prophet (PBUH) prayed two rak’ahs after the afternoon prayer.