Sirach (12:1-2) advises, “If you do good, know for whom you are doing it, and your kindness will have its effect. Do good to the just and reward will be yours (antapodoma), if not from him, from the Lord.”
This sounds like Proverbs: “He who is kind to the poor lends to the Lord, and he will reward him for what he has done.” Both Sirach and Solomon speak of reciprocity, reward for good done and specifically reward from the Lord.
But there has been a sea change between the two, evident in Sirach’s qualifying phrases, “to the just” and “if not from him.” As Petterman (Paul’s Gift from Philippi: Conventions of Gift Exchange and Christian Giving (Society for New Testament Studies Monograph Series)) says, Sirach assumes that “the just man will feel the appropriate social pressure to repay,” and he adds that “this is a teaching we do not find in the Old Testament” (41).
Jesus is in line with Proverbs, but radicalizes the instruction: ”Do not invite your friends or your brothers . . . lest they also invite you in return, and repayment (antapodoma) come to you” (Luke 14:12). Repayment from the beneficiary is precisely what we do not seek. Jesus promises repayment, but “at the resurrection of the righteous” (vv. 13-14). Neither Solomon nor Jesus imagine any “if not from him.” The reward is simply, strictly, “from the Lord.”
Besides, the people Jesus tells His disciples to invite to the table are the “poor, the crippled, the lame, the blind.” Conspicuously absent from this list are the “just.”