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.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ بْنِ قَعْنَبٍ، حَدَّثَنَا مَالِكٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ مُحَمَّدِ، بْنِ إِبْرَاهِيمَ عَنْ عَلْقَمَةَ بْنِ وَقَّاصٍ، عَنْ عُمَرَ بْنِ الْخَطَّابِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّمَا الأَعْمَالُ بِالنِّيَّةِ وَإِنَّمَا لاِمْرِئٍ مَا نَوَى فَمَنْ كَانَتْ هِجْرَتُهُ إِلَى اللَّهِ وَرَسُولِهِ فَهِجْرَتُهُ إِلَى اللَّهِ وَرَسُولِهِ وَمَنْ كَانَتْ هِجْرَتُهُ لِدُنْيَا يُصِيبُهَا أَوِ امْرَأَةٍ يَتَزَوَّجُهَا فَهِجْرَتُهُ إِلَى مَا هَاجَرَ إِلَيْهِ " .
sunnah.com