Ruling on performing Sa‘y after the Farewell Tawaaf
16-1-2014 | IslamWeb
Question:
My husband and I performed Hajj last year and we performed Sa‘y between As-Safa and Al-Marwah after performing the Farewell Tawaaf. We did not know that this is impermissible. Is our Hajj valid? Should we do something to make it valid?
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Your Hajj is valid, Allaah Willing, if you performed all its pillars and obligations properly as performing extra Sa‘y in Hajj does not affect the validity of Hajj despite the fact that performing optional Sa‘y is not permissible.
You will not be held sinful for performing Sa‘y after performing the Farewell Tawaaf out of ignorance. This is because performing Sa‘y after theFarewell Tawaaf does not violate the fact of the Sacred House being the last place where the pilgrim was before leaving Makkah. ‘Aa’ishah 
performed ‘Umrah after performing Hajj with her brother ‘Abdul-Rahmaan and she performed Tawaaf and Sa‘y. It was not reported that she performed the Farewell Tawaaf after her Sa‘y. This proves that performing Sa‘y after performing the Farewell Tawaaf does not necessitate performing another Tawaaf as Tawaaf of the ‘Umrah that was performed by ‘Aa’ishah apparently sufficed for Tawaaf the Ifaadhah and the Farewell Tawaaf.
Ibn Hajar 
said, "The story of ‘Aa’ishah indicates that if Sa‘y took place after the Tawaaf of Ifaadhah, if we said that this Tawaaf suffices for the Farewell Tawaaf, this Sa‘y that occurred between Tawaaf and leaving Makkah does not affect the validity of the abovementioned Tawaaf."
The difference between your case and that of ‘Aa’ishah is that her Sa`y is valid under Sharee`ah while yours is not and it does not affect your Hajj as you were ignorant and thought that it is valid under Sharee`ah. Another supportive point is that the action which is the object of ruling in your case and that of `Aa’ishah is the same (i.e. Sa`y).