All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
Dear brother, the hadeeth that you mentioned is a saheeh (sound) hadeeth that was reported by Muslim in his Saheeh and by Ahmad in his Musnad with some difference in its wording.
The wording of the hadeeth reported by Imaam Ahmad in his Musnad is as follows, “Miqdaam ibn Shurayh ibn Haani said, 'I heard my father reporting that he had heard ‘Aa’ishah say, 'I was once riding a difficult (slow-moving) camel, so I kept hitting it. When the Prophet saw me, he said, 'Be gentle, for gentleness adorns everything in which it is found, and its absence leaves everything tainted (defective).'''”
Shu'ayb Al-Arnaa'oot, while reviewing the Musnad of Imaam Ahmad, said, “Its chain of narrators is saheeh according to the criteria set by Muslim.”
The hadeeth was also reported by Al-Bukhari in Al-Adab Al-Mufrad with the same wording of that of Imaam Ahmad, and Al-Albaani classified it as saheeh.
This hadeeth highlights the importance of having gentleness. Ibn Hajar said, “Gentleness is to be soft in words and actions and to take the easiest option, and it is the opposite of violence and harshness.”
Allaah knows best.