Sahih Muslim Book 20, Hadith Number 4597.

Chapter : No migration after the conquest of Mecca but allegiance could be sworn (to a rightful leader) on serving the cause of Islam, on fighting in the way of Allah and on following the path of virtue.

It has been narrated on the authority of Ibn ‘Abbas that the Messenger of Allah (may peace be upon him) said on the day of the Conquest of Mecca: There is no Hijra now, but (only) Jihad (fighting for the cause of Islam) and sincerity of purpose (have great reward); when you are asked to set out (on an expedition undertaken for the cause of Islam) you should (readily) do so.