Musnad Ahmad

It is narrated from Hazrat Amr bin Abasah (may Allah be pleased with him) that once I submitted in the court of the Messenger: O Messenger of Allah! Teach me something from the knowledge that Allah has given you. The Prophet (peace and blessings be upon him) said: "When you have performed the Fajr prayer, refrain from offering voluntary prayers until the sun rises. Even when the sun rises, do not pray until the sun has risen high, because when it rises, it rises between the two horns of Satan, and at that time the disbelievers prostrate to it. However, when it has risen to the height of one or two spears, then you may pray, for this is the time when the angels are present at the prayer, until the shadow of the spear begins to appear, then refrain from prayer, for at that time Hell is stoked. But when the shadow declines, you may pray, for in this prayer too the angels are present, until you have performed the Asr prayer. After the Asr prayer, refrain from offering voluntary prayers until sunset, for it sets between the two horns of Satan and at that time the disbelievers prostrate to it."