What is Goodness in Islam?

This is the most comprehensive authentic Hadith I know of regarding what Islam teaches us about “goodness”.

Jabir bin Sulaym narrated:

لَقِيتُ رَسُولَ اللَّهِ صلى الله عليه وسلم فِي بَعْضِ طُرُقِ الْمَدِينَةِ، ‌وَعَلَيْهِ ‌إِزَارٌ ‌مِنْ ‌قُطْنٍ ‌مُنْبَتِرُ الْحَاشِيَةِ، فَقُلْتُ: عَلَيْكَ السَّلَامُ يَا رَسُولَ اللَّهِ، فَقَالَ: «إِنَّ عَلَيْكَ السَّلَامَ تَحِيَّةُ الْمَوْتَى، إِنَّ عَلَيْكَ السَّلَامَ تَحِيَّةُ الْمَوْتَى، إِنَّ عَلَيْكَ السَّلَامَ تَحِيَّةُ الْمَوْتَى، سَلَامٌ عَلَيْكُمْ، سَلَامٌ عَلَيْكُمْ» مَرَّتَيْنِ أَوْ ثَلَاثًا هَكَذَا ” قَالَ. سَأَلْتُ عَنِ الْإِزَارِ؟ فَقُلْتُ: أَيْنَ أَتَّزِرُ؟ فَأَقْنَعَ ظَهْرَهُ بِعَظْمِ سَاقِهِ، وَقَالَ: «هَاهُنَا اتَّزِرْ، فَإِنْ أَبَيْتَ، فَهَاهُنَا أَسْفَلَ مِنْ ذَلِكَ، فَإِنْ أَبَيْتَ، فَهَاهُنَا فَوْقَ الْكَعْبَيْنِ، فَإِنْ أَبَيْتَ فَإِنَّ اللَّهَ عز وجل لَا يُحِبُّ كُلَّ مُخْتَالٍ فَخُورٍ» قَالَ: وَسَأَلْتُهُ عَنِ الْمَعْرُوفِ؟ فَقَالَ: ” لَا تَحْقِرَنَّ مِنَ الْمَعْرُوفِ شَيْئًا، وَلَوْ أَنْ تُعْطِيَ صِلَةَ الْحَبْلِ، وَلَوْ أَنْ تُعْطِيَ شِسْعَ النَّعْلِ، وَلَوْ أَنْ تَنْزِعَ مِنْ دَلْوِكَ فِي إِنَاءِ الْمُسْتَسْقِي، وَلَوْ أَنْ تُنَحِّيَ الشَّيْءَ مِنْ طَرِيقِ النَّاسِ يُؤْذِيهِمْ، وَلَوْ أَنْ تَلْقَى أَخَاكَ، وَوَجْهُكَ إِلَيْهِ مُنْطَلِقٌ، وَلَوْ أَنْ تَلْقَى أَخَاكَ فَتُسَلِّمَ عَلَيْهِ، وَلَوْ أَنْ تُؤْنِسَ الْوَحْشَانَ فِي الْأَرْضِ، وَإِنْ سَبَّكَ رَجُلٌ بِشَيْءٍ يَعْلَمُهُ فِيكَ، وَأَنْتَ تَعْلَمُ فِيهِ نَحْوَهُ، فَلَا تَسُبَّهُ فَيَكُونَ أَجْرُهُ لَكَ وَوِزْرُهُ عَلَيْهِ، وَمَا سَرَّ أُذُنَكَ أَنْ تَسْمَعَهُ فَاعْمَلْ بِهِ، وَمَا سَاءَ أُذُنَكَ أَنْ تَسْمَعَهُ فَاجْتَنِبْه. “

“I came to Madinah and met the Messenger of Allah in some alley. At that time, the Prophet was wearing a lower garment made of cotton, with its ends puffed up. I said: “O Messenger of Allah! Alaika As-Salam (Upon you be peace)!”

He said: “Upon you be peace is the greeting of the dead! Upon you be peace is the greeting of the dead! Upon you be peace is the greeting of the dead! Say Salam Alaikum (Peace be upon you), peace be upon you!”

I then asked: “How high should my lower garment be?”

So the Prophet exposed his leg and pressed his shin bone and said: “Tie your lower garment till here. If you cannot do this, then tie it a little lower. If you still can’t do this, then tie it just above your ankles. If you still can’t do this, then Allah does not like those who are self-deluded and arrogant.”

I then asked him to exhort me on the subject of goodness, so he said: “Do not undermine any good deed that is performed, whether it is gifting a piece of rope, giving a shoelace, pouring water from your bucket in the vessel of a thirsty person, removing something from a path which could harm others, meeting your Muslim brother with a cheerful countenance, greeting your Muslim brother with the greetings of peace, and befriending and showing affection to those who are seen as strangers in the lands. If someone speaks ill of you based on something he knows of you which is personal to you, then do not speak ill of him in return if you have knowledge of something that is personal to him, for this will be a source of rewards for you, and a source of destruction for him. And act upon that which your ears like to hear, and abstain from that which your ears dislike to hear.”

Musnad Ahmad 15955, As-Sahihah 3422; Sahih