It is permissible to fulfill a commandment that partially involves Heaven and partially involves people with the intention of receiving a reward. This is what is meant in Scripture by "to keep the way of the LORD by doing what is just and right", which contains two parts: One concerns people – what is just (charity), that benefits people, and what is right – to instill peace between man and his brethren, and to rescue the oppressed from their oppressors… The text says, "Justice, justice shall you pursue, that you may thrive" about which our Sages, of blessed memory, said and as I understand its literal meaning: "Justice, justice" – one for judgement and one for compromise"; it is permitted to act in order to obtain receive a reward, which is why it says: "...pursue, that you may thrive".