Sunan Ibn Mājah 3436

The full narration

It was narrated that Usamah bin Sharik said:“I saw the Bedouins asking the Prophet (ﷺ): ‘Is there any harm in such and such, is there any harm in such and such?’ He said to them: ‘O slaves of Allah! Allah has only made harm in that which transgresses the honor of one’s brother. That is what is sinful.’ They said: ‘O Messenger of Allah! Is there any sin if we do not seek treatment?’ He said: ‘Seek treatment, O slaves of Allah! For Allah does not create any disease but He also creates with it the cure, except for old age.’ They said: ‘O Messenger of Allah, what is the best thing that a person may be given?’ He said: ‘Good manners.’”