Sunan an-Nasa'i, Hadith 3169 ⓘ
It was narrated from Zurah bin Ma'bad: "Abu Salih, the freed slave of 'Uthman, said: 'I heard 'Uthman bin 'Affan say: I heard the Messenger of Allah say: Ribat (guarding the frontier) for one day in the cause of Allah is better in rank than a thousand days spent within the residence.'"
أَخْبَرَنَا عَمْرُو بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ زَهْرَةَ بْنِ مَعْبَدٍ، قَالَ حَدَّثَنِي أَبُو صَالِحٍ، مَوْلَى عُثْمَانَ قَالَ سَمِعْتُ عُثْمَانَ بْنَ عَفَّانَ، رضى الله عنه يَقُولُ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " رِبَاطُ يَوْمٍ فِي سَبِيلِ اللَّهِ خَيْرٌ مِنْ أَلْفِ يَوْمٍ فِيمَا سِوَاهُ مِنَ الْمَنَازِلِ " .
also referenced under: Book 25, Hadith 85 (In-Book) & Volume 4, Book 25, Hadith 3171 (DarusSalam)