Sunan an-Nasa'i 3144
It was narrated that Shurahbil bin As-Simt said to Ka'b bin Murrah:
"O Ka'b! Tell us a Hadith from the Messenger of Allah (ﷺ) and be careful." He said: "I heard him say: 'Whoever develops one gray hair in Islam, in the cause of Allah, it will be light for him on the Day of Resurrection.'" He said to him: "Tell us about the Prophet (ﷺ) and be careful." He said: "I heard him say: 'Shoot, and whoever hits the enemy with an arrow, Allah will raise him one degree in status thereby.'" Ibn An-Nahhan said: 'O Messenger of Allah, what is a degree?' He said: 'It is not like the doorstep of your mother; [1] rather (the distance) between two degrees is (that if) a hundred years.'"

[1] As explained after it; the degree of distance is greater than such a degree in this world.
أَخْبَرَنَا مُحَمَّدُ بْنُ الْعَلاَءِ، قَالَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، قَالَ حَدَّثَنَا الأَعْمَشُ، عَنْ عَمْرِو بْنِ مُرَّةَ، عَنْ سَالِمِ بْنِ أَبِي الْجَعْدِ، عَنْ شُرَحْبِيلَ بْنِ السِّمْطِ، قَالَ لِكَعْبِ بْنِ مُرَّةَ يَا كَعْبُ حَدِّثْنَا عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم وَاحْذَرْ ‏.‏ قَالَ سَمِعْتُهُ يَقُولُ ‏"‏ مَنْ شَابَ شَيْبَةً فِي الإِسْلاَمِ فِي سَبِيلِ اللَّهِ كَانَتْ لَهُ نُورًا يَوْمَ الْقِيَامَةِ ‏"‏ ‏.‏ قَالَ لَهُ حَدِّثْنَا عَنِ النَّبِيِّ صلى الله عليه وسلم وَاحْذَرْ ‏.‏ قَالَ سَمِعْتُهُ يَقُولُ ‏"‏ ارْمُوا مَنْ بَلَغَ الْعَدُوَّ بِسَهْمٍ رَفَعَهُ اللَّهُ بِهِ دَرَجَةً ‏"‏ ‏.‏ قَالَ ابْنُ النَّحَّامِ يَا رَسُولَ اللَّهِ وَمَا الدَّرَجَةُ قَالَ ‏"‏ أَمَا إِنَّهَا لَيْسَتْ بِعَتَبَةِ أُمِّكَ وَلَكِنْ مَا بَيْنَ الدَّرَجَتَيْنِ مِائَةُ عَامٍ ‏"‏ ‏.‏