That the Messenger of Allah (ﷺ) said: "(Ribat) Guarding the frontier for a day in the cause of Allah is better than the world and what is in it. And an afternoon the worshipper spends in the cause of Allah - or a morning - is better than the world and what is on it. And the space occupied by the whip of one of you in Paradise is better than the world and what is on it." This Hadith is Hasan Sahih.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي النَّضْرِ، حَدَّثَنَا أَبُو النَّضْرِ الْبَغْدَادِيُّ، حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنْ أَبِي حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ رِبَاطُ يَوْمٍ فِي سَبِيلِ اللَّهِ خَيْرٌ مِنَ الدُّنْيَا وَمَا فِيهَا وَمَوْضِعُ سَوْطِ أَحَدِكُمْ فِي الْجَنَّةِ خَيْرٌ مِنَ الدُّنْيَا وَمَا فِيهَا وَلَرَوْحَةٌ يَرُوحُهَا الْعَبْدُ فِي سَبِيلِ اللَّهِ أَوْ لَغَدْوَةٌ خَيْرٌ مِنَ الدُّنْيَا وَمَا فِيهَا . هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ .
Tirmizi
The Book on Virtues of Jihad • Hadith 1712