Narrated Abu Sa'eed:
that about Allah's saying: Thus we have made you a Wasata nation (2:143) - the Prophet (ﷺ) said: "The meaning of Wasata is just." (ID)
English reference (ID): Vol. 5, Book 44, Hadith 2961 (ID)
Arabic reference (ID): Book 47, Hadith 3222 (ID)