Mishkat al-Masabih 210
Jarir said that:
One early morning when they were with God’s messenger some people came to him who were scantily clad, wearing striped
woollen garments,* with swords over their shoulders; most, nay all of
them, belonging to Mudar. God’s messenger showed signs of anger on
his face because of the poverty-stricken state in which he saw them,
and went in. After a little he came out and gave orders to Bilal who
uttered the call to prayer and announced that the time to begin prayer
had come. When the Prophet had prayed, he delivered an address in 
which he said, “ ‘Fear your Lord, people, who created you from one
soul . . . God watches over you.’[Qur’an, iv, 1] ‘Fear God, and let a soul look to
what it has sent forward for the morrow. [Ibid., lix, 18] Let a man give sadaqa from his dinars and dirhams, his clothing, his sa‘ of wheat and sa‘ of
dates, even if it is only half a date.” Jarir said: One of the Ansar
brought a purse which was almost too big for his hand to hold, indeed
it was too big. Then people came one after the other till I saw two
mounds of food and clothing, with the result that I saw the face of God’s
messenger glowing as if it were golden. He then said, “If anyone establishes a good sunna in Islam he will have a reward for it and the
equivalent of the rewards of those who act upon it after him, without
theirs being diminished in any respect; but he who establishes a bad sunna in Islam will bear the responsibility of it and the responsibility
of those who act upon it after him, without theirs being diminished in
any respect.” Muslim transmitted it. 
*[The text has an-nimar au al-'aba , thus giving an alternative word. This is not indicated in
the translation above.]
وَعَن جرير قَالَ: (كُنَّا فِي صدر النهارعند رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَجَاءَهُ قَوْمٌ عُرَاةٌ مُجْتَابِي النِّمَارِ أَوِ الْعَبَاءِ مُتَقَلِّدِي السُّيُوفِ عَامَّتُهُمْ مِنْ مُضَرَ بَلْ كُلُّهُمْ مِنْ مُضَرَ فَتَمَعَّرَ وَجْهُ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لِمَا رَأَى بِهِمْ مِنَ الْفَاقَةِ فَدَخَلَ ثُمَّ خَرَجَ فَأَمَرَ بِلَالًا فَأَذَّنَ وَأَقَامَ فَصَلَّى ثُمَّ خَطَبَ فَقَالَ: (يَا أَيُّهَا النَّاسُ اتَّقُوا رَبَّكُمُ الَّذِي خَلَقَكُمْ مِنْ نَفْسٍ وَاحِدَةٍ)
إِلَى آخَرِ الْآيَةِ (إِنَّ اللَّهَ كَانَ عَلَيْكُمْ رقيبا)
وَالْآيَةُ الَّتِي فِي الْحَشْرِ (اتَّقُوا اللَّهَ وَلْتَنْظُرْ نَفْسٌ مَا قَدَّمَتْ لِغَدٍ)
تَصَدَّقَ رَجُلٌ مِنْ دِينَارِهِ مِنْ دِرْهَمِهِ مِنْ ثَوْبِهِ مِنْ صَاعِ بُرِّهِ مِنْ صَاعِ تَمْرِهِ حَتَّى قَالَ وَلَوْ بِشِقِّ تَمْرَةٍ قَالَ فَجَاءَ رَجُلٌ مِنَ الْأَنْصَارِ بِصُرَّةٍ كَادَتْ كَفُّهُ تَعْجَزُ عَنْهَا بل قد عجزت قَالَ ثُمَّ تَتَابَعَ النَّاسُ حَتَّى رَأَيْتُ كَوْمَيْنِ مِنْ طَعَامٍ وَثِيَابٍ حَتَّى رَأَيْتُ وَجْهُ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَتَهَلَّلُ كَأَنَّهُ مُذْهَبَةٌ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ سَنَّ فِي الْإِسْلَامِ سُنَّةً حَسَنَةً فَلَهُ أَجْرُهَا وَأَجْرُ مَنْ عَمِلَ بِهَا مِنْ بَعْدِهِ مِنْ غَيْرِ أَنْ يَنْقُصَ مِنْ أُجُورِهِمْ شَيْءٌ وَمَنْ سَنَّ فِي الْإِسْلَامِ سُنَّةً سَيِّئَةً كَانَ عَلَيْهِ وِزْرُهَا وَوِزْرُ مَنْ عَمِلَ بِهَا مِنْ بَعْدِهِ مِنْ غَيْرِ أَنْ يَنْقُصَ مِنْ أَوْزَارِهِمْ شَيْء» . رَوَاهُ مُسلم