Muwatta 8

A report that Malik transmits from Hisham ibn Urwa from his father, in the chapter on the times of prayer: Umar ibn al-Khattab (may God be pleased with him) wrote to Abu Musa al-Ash'ari that he should pray the afternoon while the sun is white and clear by the distance a rider covers in three leagues, and pray isha between its beginning and a third of the night, and if he delays it, to half the night, and not be among the heedless. The editor notes that Abu Mus'ab, Suwayd and Yahya ibn Bukayr transmitted it from Malik, in al-Bayhaqi. ¹

Belongs to the Muwatta, Book of Prayer. Source: the Muwatta. Mentions Umar ibn al-Khattab, Abu Musa al-Ash'ari, Hisham ibn Urwa and Urwa ibn al-Zubayr. Built on in the chapters on prayer.