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." (RU)
English reference (RU): Vol. 5, Book 44, Hadith 2961 (RU)
Arabic reference (RU): Book 47, Hadith 3222 (RU)