It is narrated from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: He came to the people of Quba' while they were praying the forenoon (Duha) prayer, and said: "The prayer of the oft-repentant (al-awwabin) is when the feet of the young camels begin to burn."
(Al-Tabarani's clarification:) The narrator did not attribute this narration to the Messenger of Allah (peace and blessings be upon him) (marfu').
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5094