Nasr bin Abdur Rahman says that once he performed Tawaf of the Ka'bah with Hazrat Mu'adh bin Afraa (may Allah be pleased with him) after the Asr prayer. After the Tawaf, he did not perform the two rak'ahs of Tawaf. I asked him about this, so he replied that the Prophet (peace and blessings of Allah be upon him) said: "There is no voluntary prayer after two prayers: after the Fajr prayer until sunrise, and after the Asr prayer until sunset."