Sunan an-Nasa'i, Book 39, Hadith 19 (In-Book) ⓘ
It was narrated from Kathir bin Murrah that Abu Fatimah told him that he said: "O Messenger of Allah, tell me of an action that I may do and persist in it." The Messenger of Allah said to him: "You should emigrate, for there is nothing like it."
أَخْبَرَنِي هَارُونُ بْنُ مُحَمَّدِ بْنِ بَكَّارِ بْنِ بِلاَلٍ، عَنْ مُحَمَّدٍ، - وَهُوَ ابْنُ عِيسَى بْنِ سُمَيْعٍ - قَالَ حَدَّثَنَا زَيْدُ بْنُ وَاقِدٍ، عَنْ كَثِيرِ بْنِ مُرَّةَ، أَنَّ أَبَا فَاطِمَةَ، حَدَّثَهُ أَنَّهُ، قَالَ يَا رَسُولَ اللَّهِ حَدِّثْنِي بِعَمَلٍ، أَسْتَقِيمُ عَلَيْهِ وَأَعْمَلُهُ . قَالَ لَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم " عَلَيْكَ بِالْهِجْرَةِ فَإِنَّهُ لاَ مِثْلَ لَهَا " .
also referenced under: Hadith 4167 (Reference) & Volume 5, Book 39, Hadith 4172 (DarusSalam)