It is narrated from Urwah bin Zubair that Sayyiduna Umar bin Al-Khattab (may Allah be pleased with him) wrote to Sayyiduna Abu Musa Ash'ari (may Allah be pleased with him) that: Perform the Asr prayer while the sun is still white, and there is so much daylight left that a camel rider could travel nine miles after the Asr prayer. And perform the Isha prayer up to one-third of the night, at the latest up to half the night, and do not be negligent.