In the Lecture Late Dr. Israr Ahmed Shahib speak about very popular hadith

On the authority of the Commander of the Faithful, Abū Ḥafs, `Umar bin al-Khaṭṭāb, who said: I heard the Messenger of Allah () say: "Deeds are only by intentions, and every man shall have only what he intended. So one whose hijrah [emigration] was to Allah and His Messenger – his hijrah was to Allah and His Messenger. But one whose hijrah was to achieve a worldly aim or to a woman he would marry – then his hijrah was to that for which he emigrated."