وَأَوَّلُ وَقْتِ الظُّهْرِ إِذَا زَالَتِ الشَّمْسُ، وَآخِرُ وَقْتِهَا عِنْدَ أَبِي حَنِيفَةَ إِذَا صَارَ ظِلُّ كُلِّ شَيْءٍ مِثْلَيْهِ سِوَى فَيْءِ الزَّوَالِ
Translation: Dhuhr begins after the sun passes its zenith. According to Abu Hanifah it ends when an object’s shadow, excluding its noon shadow, becomes twice the object’s length.
The difference of opinion concerns the ending boundary. The noon shadow excluded by the phrase “apart from the noon shadow” must be accounted for.