Al-Qasim al-Shaybani (may Allah have mercy on him) said that Sayyiduna Zayd bin Arqam (may Allah be pleased with him) saw some people praying the Duha prayer in the Mosque of Quba and said: Yet they know that praying at a time other than this is better. The Messenger of Allah (peace and blessings be upon him) said: "The time of the prayer of the awwabin (those who constantly turn to Allah) is when the feet of the young camels begin to burn." And once he said: when people were praying.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4908
Al-Qasim al-Shaybani (may Allah have mercy on him) narrates from Sayyiduna Zayd bin Arqam (may Allah be pleased with him) that he saw people sitting with a storyteller; when the sun rose, they hurried to the pillars of the mosque and began praying. So Sayyiduna Zayd bin Arqam (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "The time of the prayer of the awwabin is when the feet of the young camels begin to burn."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4909
Al-Qasim bin Abd al-Rahman narrates from Sayyiduna Abu Umamah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever comes in a state of ablution to offer an obligatory prayer, his reward is like the reward of one performing Hajj in ihram; whoever comes to offer the voluntary Duha prayer, with nothing but it making him set out, his reward is like the reward of one performing Umrah; and a prayer offered after a prayer, with no idle talk between them, is recorded in Illiyyin."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4910