Fiqh-us-Sunnah Volume 005, Hajj and 'Umrah, Fiqh 5.014B.

Section : Hajj in Fulfilment of a Vow While Having to Perform Obligatory Hajj.

According to the verdict of Ibn 'Abbas and 'Ikrimah if a person performs Hajj in fulfilment of a vow, while he has yet to perform the prescribed Hajj, then it should suffice him (and absolve him) from both. 'Ata and Ibn 'Umar, on the other hand, hold that one must first perform the Hajj obligatory on him, and thereafter perform another Hajj to fulfil his vow.