Sayyiduna Amr bin Abasah (may Allah be pleased with him) said: I said: O Messenger of Allah, in which part of the night is (supplication) most heard? He (peace and blessings be upon him) said: "In the last part of the night. Pray as much as you wish, for the angels are present at that prayer, until the Subh prayer is prayed. Then refrain from prayer while the sun is rising, until the sun has risen the height of one or two spears; it rises between the two horns of the devil, and the disbelievers prostrate to it. Then pray as much as you wish, for the angels are present at that prayer, until the shadow is equal to a spear. Then refrain from prayer, for at that time Hell is stoked and its gates are opened. When the sun has declined, pray as much as you wish; the angels are present at this prayer as well, until you pray the Asr prayer. Then refrain from prayer until the sun sets, for it sets between the two horns of the devil and the disbelievers prostrate to it." The narrator said: Then he narrated a long hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4386