Sahih Bukhari Volume 5, Book 63, Hadith 3900

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا حَمَّادٌ ـ هُوَ ابْنُ زَيْدٍ ـ عَنْ يَحْيَى، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ بْنِ وَقَّاصٍ، قَالَ سَمِعْتُ عُمَرَ ـ رضى الله عنه ـ قَالَ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ ‏"‏ الأَعْمَالُ بِالنِّيَّةِ، فَمَنْ كَانَتْ هِجْرَتُهُ إِلَى دُنْيَا يُصِيبُهَا أَوِ امْرَأَةٍ يَتَزَوَّجُهَا، فَهِجْرَتُهُ إِلَى مَا هَاجَرَ إِلَيْهِ، وَمَنْ كَانَتْ هِجْرَتُهُ إِلَى اللَّهِ وَرَسُولِهِ، فَهِجْرَتُهُ إِلَى اللَّهِ وَرَسُولِهِ صلى الله عليه وسلم ‏"‏‏

Narrated By 'Umar : I heard the Prophet saying, "The reward of deeds depends on the intentions, so whoever emigrated for the worldly benefits or to marry a woman, his emigration was for that for which he emigrated, but whoever emigrated for the Sake of Allah and His Apostle, his emigration is for Allah and His Apostle."