and one hundred when he prolonged it [al-Bukhārī 516; Muslim 647], always reciting in a measured, deliberate manner—may Allah bless him and grant him peace.

2 – We have interpreted the instruction to “let the morning grow bright” as a command to lengthen the recitation, so that this report accords with the Prophet’s ﷺ established practice of beginning the prayer in ghalas, the deep darkness that lingers at the end of the night.

3 – Performing the dawn prayer at its earliest time while extending the recitation is the view adopted by the majority of scholars, including the three leading Imams.
As for the Ḥanafīs, they prefer delaying it, arguing from the outward sense of this hadith and maintaining that it represents the Prophet’s ﷺ final practice.