Zayd ibn Arqam (may Allah be pleased with him) saw some people pray in the forenoon, so he said that he heard the Prophet (may Allah's peace and blessings be upon him) say that the prayer of the oft-returning to Allah is when the heat is so scorching that the hooves of little camels burn on the ground. That is the best time to pray the Duha prayer for those who obey Allah and often return to Him.