Must a person re-perform the independent reasoning (Ijtihad) for subsequent prayers if they change direction based on new Ijtihad?

Primary text

If a person performs prayer based on an initial effort of Ijtihad regarding the Qibla direction, and then intends to perform another prayer, re-establishing the Ijtihad for the subsequent direction is obligatory. This is the established view of Al-Shafi'i. If the initial Ijtihad changes, the latter ruling is acted upon, and the prayer performed under the first Ijtihad is not repeated. This is analogous to a judge whose Ijtihad changes; the new ruling applies to subsequent matters, and the previous judgment is not overturned. This principle of not overturning previous acts based on a change in Ijtihad for future acts is universally accepted. If one's Ijtihad in prayer changes, one must turn toward the new direction and build upon the previously performed prayer. This position was explicitly stated by Ahmad in the narration reported by the majority group.