on the authority of abu dharr jundub ibn junaadah, and abu 'abd-ir-rahmaan mu'aadh bin jabal (radiallaahu anhumaa) that the messenger of allaah (sallallaahu alayhi wa sallam) said :

it was related by at-tirmidhee, who said it was a hasan (good) hadeeth, and in some copies it is stated to be a hasan saheeh hadeeth.

explanation of hadeeth number 18

the virtues and outstanding traits of abu dharr (radiallaahu anhu) are many. he accepted islaam while the messenger of allaah (sallallaahu alayhi wa sallam) was still in makkah, and was instructed by him to return to and keep close to his tribe [in order to call them to islaam]. however, when the prophet (sallallaahu alayhi wa sallam) saw in him a great eagerness to remain with him in makkah, and knowing that he would not be able to do so [due to the torment of the quraysh], he said to abu dharr : "have taqwaa (fear) of allaah wherever you may be, and follow up a bad deed with a good deed which will wipe it out", and this is in accordance with the statement of allaah ta'aalaa "verily, the good deeds remove the evil deeds" [hood, 114].

and his (sallallaahu alayhi wa sallam) statement "and behave well towards the people" means that one should treat the people the way one would like them to treat oneself. and know that "verily the heaviest thing to be placed in the scales [on the day of accounting] will be the good character/behaviour". and the messenger of allaah (sallallaahu alayhi wa sallam) is reported to have said "verily the most loved of you by me and the closest of you to me on the day of resurrection are the best of you in character" [related by at-tabaraanee, but judged weak by al-haafidh al-mundhiree in at-targheeb wa at-tarheeb]. and good character is from the characteristics of the prophets and messengers and the chosen ones from amongst the believers - those who do not retaliate with evil, but rather forgive and pardon and behave well despite being treated badly.

summary :

• that one must remember allaah with fear no matter where he may be
• that one must do a good act to cover up each bad act that he commits
• that a muslim must behave well towards others