Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "There is no prayer after Fajr until the sun rises, and no prayer after Asr until the sun sets. Whoever performs tawaf of the House of Allah, let him pray at whatever time he performs tawaf."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4417