Intention for An-Nusk.

When the person intending Ihram has finished bathing and cleaning himself and has worn his Ihram garments, and (a male) has taken off any fitted garments, he then makes the intention to commence An-Nusk, either for Hajj or �Umrah. It is recommended to state clearly the sequence of Nusk the person intends to perform. For instance he says, when he wishes to perform at-Tamattu�, i.e. �Umrah, after which he becomes released (i.e. free and disengaged from the obligations of ihram) before starting Hajj: �Labbaykal-Laahumma �Umuratan mutamat-ti�an biha ilal Hajj: �O Allah, I have answered Your call and here I am to serve You through �Umrah, after which I will become released (from the obligations of ihram) until I start Hajj,� or �Labbaykal-Laahumma �Umura�: �O Allah, I have answered Your call and here I am to serve You through �Umrah.� Then at Hajj he says: �Labbaykal-Laahumma Hajjan�: �O Allah, I have answered Your call and I am ready to serve You through Hajj.� And the person who intends Hajj al-Ifrad (Hajj alone) says; �Labbaykal-Laahumma Hajjan�: �O Allah, I have answered Your call and here I am to serve You through Hajj�; while the person who intends to merge Hajj and �Umrah together (Qiraan) says: �Labbaykal-Laahumma Hajjan wa �Umurah�: �O Allah, I have answered Your call and here I am to serve You through Hajj and �Umrah.� This is according to the hadeeth by Anas t, who said: �I heard the Messenger of Allah ﷺ say: �O Allah, I answered Your call and here I am to serve You through Hajj and �Umrah.� [ Agreed upon.] However, if one does not pronounce anything, the intention he made in his mind is enough.
Source: islamkingdoman-nusk