What is the exact transition point between Dhuhr and Asr times?
Chapter on Prayer Times
Al-Mughni
Book of Prayer
Primary text
The transition from Dhuhr time to Asr time occurs immediately upon the slightest increase beyond the shadow length being equal to the object's height. There is no separation between the two times; when the shadow equals the object, Dhuhr ends, and Asr begins. This is the position of Al-Shafi'i and is considered close to the opinion of Al-Kharqi.
Supporting text
Abu Hanifa argued the time extends until the shadow is twice the object's height, citing Quran 11:114, '{Establish prayer at the two ends of the day}', asserting that anything less would be considered the middle of the day. Rabi'ah suggested that the time for Dhuhr and Asr begins immediately upon *zawwal*.