Musannaf Ibn Abi Shaybah

Hazrat Ata says that I saw Ibn Umar (may Allah be pleased with them both) and Ibn Zubair perform Tawaf of the Ka'bah before Fajr, then before sunrise both of them offered (Tawaf) prayer. And (Imam) Abu Hanifa's opinion has been mentioned that: One should not pray until the sun rises or sets, and until it is possible to pray.