The question of performing sa'i before tawaf is one of the issues where scholars have significant differences of opinion. The majority of scholars — the Maliki, Shafi'i, and the well-known Hanbali position — hold that tawaf must precede sa'i, and sa'i performed before tawaf is invalid and must be repeated after performing tawaf. Their evidence is that Nabi (shallallahu alaihi wa sallam) performed tawaf before sa'i in all his ibadah hajis, and he said: 'Take your rites from me,' establishing that his order is to be followed.
The Hanafi school takes a different position, holding that while performing tawaf before sa'i is the Sunnah and preferred order, sa'i performed before tawaf is valid, though it is contrary to the sunnah practice. This is based on the hadith narrated on the Day of Sacrifice when a man came to Nabi and said: 'I performed sa'i before tawaf,' and Nabi replied: 'No harm' (la haraja), indicating that the order is not a strict condition.
Sheikh Ibn Taymiyyah supported the view that the order between tawaf and sa'i is sunnah but not wajib, citing the hadith about Nabi's response on the Day of Sacrifice. Ibn Uthaymeen, while generally following the majority position, acknowledged that the hadith provides evidence for flexibility. He sunnah following the established order (tawaf then sa'i) as the safe and clear practice, while acknowledging that some scholars validate the reversed order based on the explicit hadith.