If you performed the obligatory Hajj of Islam previously, then you do not have to do anything. However, if you did not perform the obligatory Hajj before, then you should hasten to do Hajj as soon as you can. Sheikh Ibn `Uthaymeen, a prominent Saudi Muslim scholar, (may Allah shower mercy on his soul), said that: If the person who is doing tamattu` enters ihram then he decides, after `Umrah and before he enters ihram for Hajj, not to perform Hajj, then he does not have to do anything, unless he had made a vow. If he made a vow to perform Hajj this year then he has to fulfill his vow, but if he did not make a vow then there is no blame on him if he does not perform Hajj after doing `Umrah.