"It was said, 'O Messenger of Allah, what equals Jihad?' He said: 'Verily, you (people) are not capable of it.' So they repeated it to him two or three times, each time he said, 'You (people) are not capable of it.' Then he said the third time: 'The example of the Mujahid in the path of Allah is like the one who fasts and stands (in prayer) and does not slacken from Salat, nor fasting, until the Mujahid in the cause of Allah returns.'" There are narrations on this topic from Ash-Shifa', 'Abdullah bin Hubshi, Abu Musa', Abu Sa'eed, Umm Malik Al-Bahziyyah, and Anas. This Hadith is a Hasan Sahih. And it has been reported through more than one route from Abu Hurairah from the Prophet (ﷺ).
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ سُهَيْلِ بْنِ أَبِي صَالِحٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قِيلَ يَا رَسُولَ اللَّهِ مَا يَعْدِلُ الْجِهَادَ قَالَ " لاَ تَسْتَطِيعُونَهُ " . فَرَدُّوا عَلَيْهِ مَرَّتَيْنِ أَوْ ثَلاَثًا كُلُّ ذَلِكَ يَقُولُ " لاَ تَسْتَطِيعُونَهُ " . فَقَالَ فِي الثَّالِثَةِ " مَثَلُ الْمُجَاهِدِ فِي سَبِيلِ اللَّهِ مَثَلُ الْقَائِمِ الصَّائِمِ الَّذِي لاَ يَفْتُرُ مِنْ صَلاَةٍ وَلاَ صِيَامٍ حَتَّى يَرْجِعَ الْمُجَاهِدُ فِي سَبِيلِ اللَّهِ " . قَالَ أَبُو عِيسَى وَفِي الْبَابِ عَنِ الشَّفَاءِ وَعَبْدِ اللَّهِ بْنِ حُبْشِيٍّ وَأَبِي مُوسَى وَأَبِي سَعِيدٍ وَأُمِّ مَالِكٍ الْبَهْزِيَّةِ وَأَنَسِ بْنِ مَالِكٍ . وَهَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ وَقَدْ رُوِيَ مِنْ غَيْرِ وَجْهٍ عَنْ أَبِي هُرَيْرَةَ عَنِ النَّبِيِّ صلى الله عليه وسلم .
Tirmizi
The Book on Virtues of Jihad • Hadith 1666