59 In earlier Jewish traditions, the imperative to love and care for others appears to have been limited to relationships between members of the same nation. The ancient commandment to “love your neighbour as yourself” ( Lev 19:18) was usually understood as referring to one’s fellow citizens, yet the boundaries gradually expanded, especially in the Judaism that developed outside of the land of Israel. We encounter the command not to do to others what you would not want them to do to you (cf. Tob 4:15). In the first century before Christ, Rabbi Hillel stated: “This is the entire Torah. Everything else is commentary”. The desire to imitate God’s own way of acting gradually replaced the tendency to think only of those nearest us: “The compassion of man is for his neighbour, but the compassion of the Lord is for all living beings” ( Sir 18:13).
Source: Fratelli Tutti (Vatican.va)