From Sahih Muslim (Hadith 4927):
It has been narrated on the authority of Umar b. al-Khattab that the Messenger of Allah (ﷺ) said:(The value of) an action depends on the intention behind it. A man will be rewarded only for what he intended. The emigration of one who emigrates for the sake of Allah and His Messenger (ﷺ) is for the sake of Allah and His Messenger (ﷺ) ; and the emigration of one who emigrates for gaining a worldly advantage or for marrying a woman is for what he has emigrated
Reference: Muslim 4927