Is the prohibition on praying after the Fajr prayer related to the time or the act of praying Fajr?
Chapter on the Times When Prayer is Prohibited
Al-Mughni
Book of Prayer
Primary text
The prohibition after Fajr prayer is related to the rising of the sun, meaning the prohibition applies to the time period following the dawn, regardless of when Fajr prayer was performed. This is the position of Sa'id ibn al-Musayyab, al-'Ala' ibn Ziyad, Humayd ibn 'Abd al-Rahman, and the proponents of the opinion. Evidence suggests this, as the wording in some authentic narrations addresses the time after the Fajr prayer until sunrise, similar to the general time-based prohibition.
Supporting text
Another narration attributed to Imam Ahmad states that the prohibition after Fajr, like the one after Asr, is related to the performance of the prayer itself. This is supported by Hadith that links the cessation of prayer to the completion of the Fajr prayer, and because the prohibition occurs after an obligatory prayer, suggesting it mirrors the ruling after Asr.